Best Alt Mode and Best Robot Mode in Your Collection

[Ode to a Grasshopper]

These are really tough questions...

Yeah, I've gotta give it to Bludgeon-with-upgrade-kit for best 'bot mode too. MP Soundwave would be a really close second.
I'm also really find of Animated Jazz for some reason. It's just a classic hood-as-chest Autobot car, but it just works somehow. Same thing for RotF Recon Ironhide.
Totally agree with NEST Deluxe Brawn being really underrated btw. Voyager Mindwipe deserves an honorable mention too.

Best alt-mode? That's tough too...I'm not sure about 'best' exactly, but BW Transmetal 2 Megatron is definitely my favourite.
Unless we're counting 3rd Party, and then it's MMC Anarchus all the way, because an electric chair Transformer with empty, dead eyes is freaking cool...

[Deonasis]

Despite the robot underneath i cannot look past rotf Jetfire for alt-mode. Its huge size is so fitting for that beautiful SR-71. One of the few robots i display in alt mode, even over his deadbody superarmour optimus mode.

So many robot shapes i enjoy.. chug Cyclonus has a great lean aesthetic they could have built a series around. Magmatron screams 1980s villian. More to come.

[GoktimusPrime]

Best Robot Mode: MP10 Convoy; looks good, loads of features and heaps of fun to play with

Best Alt Mode: Alternity Bumblebee
As I said in my Cybertron Collectors video, one thing that I find endearing about G1 Bumblebee is the unassuming alt mode that epitomises being a robot in disguise. Flashy sports cars and race cars are more eye-catching and less useful as disguise modes since they're more likely to draw attention.

A little yellow Suzuki Swift works really well, as these are cars that I commonly see on streets. And yeah, it's not a unique thing - there are plenty of other Transformers out there with unassuming alt modes that work well as disguises too (including most BTs and Alternities). Even in early G1 we had toys like Trailbreaker, Hoist, Ironhide, Bluestreak, Hound etc.; all vehicles that wouldn't look out of place parked on a residential street or in a car park. I really like Bumblejumper too - the good ol' Mazda 323! Heck, this morning I saw a Ford Mustang GT drive past me and I immediately thought of BT Grimlock/Wheeljack.

As far as beast modes are concerned, my favourite would be K-9. A German shepherd dog would easily blend in with human society (and pre-cartoon BW canon was meant to be set in the modern day!). Insect and arachnid modes are also pretty cool if they can mass-shrink down to the size of actual bugs, as the G1 Insecticons did in the Marvel comics (and same with ROTF Insecticon). This allows them to infiltrate practically anywhere. And the Autobot Pretenders in Japanese G1 also worked well as they could mass shrink down to human size and walk around wearing human clothes. Seriously, being able to disguise yourself as a human is pretty damn handy on Earth. Although technically these are shells, not alt modes -- but ROTF's Pretender Alice had a human alt mode (although her transformation and robot mode were bollocks). It's weird how Anglophone G1 continuity never tried mass-shrinking the Pretenders and so their disguises only worked once against some very naive/stupid Decepticons, and after that only on off-world locations inhabited by giant human-like aliens (e.g. Femax, Pz'Zazz, VsQs etc.).

[CHILENO20]

My fav alt mode is definitely Generations Jetfire. I love how it homages the original Jetfire and I'm unashamedly a Macross/Robotech fan. I've always been partial to jets anyway.

[GoktimusPrime]

My fav alt mode is definitely Generations Jetfire. I love how it homages the original Jetfire and I'm unashamedly a Macross/Robotech fan. I've always been partial to jets anyway.

I really love how the toy is basically flipping the bird at Harmony Gold after HG's failed lawsuit against Hasbro.

[UltraMarginal]

This is a really hard question.
I love the Alt modes that really look like they could be rea. as such, a whole lot of the movie toys hit that target. The Twins Icecream truck is a standout.

ROTF Mindwipe is outstanding, having no real robot kibble at all in vehicle mode.

I bought MP G2 Sideswipe entirely on the strength of him being a black Lamborghini.

The generations Junkion mould is the best looking motorbike that has ever been produced by the brand in my mind.

The first MP Starscream looked like a model plane it has that good an alt mode.

favourite bot mode:
ROTF Demolisher has a really unique interesting bot mode, on top of having a very realistic looking alt mode.

The teen Masterpieces, have a great visual aesthetic, what the cartoon characters would look like if they actually transformed from 'real' looking alt modes, the lambos, datsuns, Wheeljack and Tracks all look outstanding in bot mode (and alt mode)

MP soundwave, is pretty much a perfect soundwave.

[GoktimusPrime]

Okay, I'm gonna go through my collection and pick a stand out alt mode from each year. Again, I'm particularly drawn to modes that look or work well as robots in disguise.

1984: Soundwave. Realistically scaled radio microcassette player where the AA batteries even become the weapons! Also, 5mm posts FTW.
1985: Downshift. What a silly-car is the Celica.
1986: Ultra Magnus. Okay, the trailer is unrealistic, but the interplayability with other Autobot Cars is just too much fun. It was always so cool making him haul other Autobots to battle. It's a shame that the scene of Ultra Magnus doing this in the Battle of Autobot City was deleted from Transformers The Movie.
1987: Goldbug. Finally, a realistically proportioned Volkswagen Beetle.
1988: Nightbeat. Okay, the chopper flames on the side of a blue Porsche 959 aren't standard, but also not as conspicuous as the racing decoes on Jazz!
1989: Swindler. Great Scott, he's a DeLorean! Honourable mention to Greasepit for his service station base!
1990: Big Daddy. A 1957 Chevy, and that name!
1991: Joe, the Super Hitachi Express train. I've been on this train a few times in Japan.
1992: Discharge, the cute little fire engine with the funny name.
1993: Optimus Prime. Yeah, I don't own too many toys from the G2 era (my collecting slowed down during this time), but hey, it's a Freightliner FL86, it works. Ignore the huge stickers on the sides of the trailer.
1994: Skram; Chevrolet Corvette Stingray with exposed engine.
1995: Frenzy. Another Porsche 959 only without attention-drawing chopper flames. And yay, another Decepticon on this list!
1996: Insecticon. Yeah, a lot of the early BW toys had realistic looking beast modes, but a beetle would be able to sneak about human society without being noticed (assuming that he can mass-shift down to the size of an actual insect). And remember that pre-cartoon BW continuity was set on modern day Earth, so my BW picks are based on this assumption.
1997: K-9. As mentioned before, a German shepherd dog. A popular pet and wouldn't look out of place.
1998: Big Mos. Don't forget the Aeroguard.
1999: Mach Kick. No horsing around.
2000: Super Fire Convoy; Hino Branbilar fire engine.
2001: X-Brawn; Mercedes Benz ML320
2002: Crosscut; Honda City R hatchback. Yeah, I know I'm picking a Diaclone mould that was basically reissued as a Transformer character, but 2002 was a crap year for TF collecting with bugger all new toys released.
2003: Binaltech Lambor; Dodge Viper SRT-10
2004: BT Jazz; Mazda RX-8. Zoom-zoom. Special mention to Hound/Swindle, Jeep Wranglers.
2005: BT Overdrive; Honda S2000.
2006: Alternator Mirage; Ford GT. And one of the few Alternators that I consider superior to its BT counterpart.
2007: Speed Dial 800; mobile phone. We all have one. Special mention to Frenzy.
2008: Stockade; modified Cadillac Escalade SUV.
2009: Alternity Bumblebee; Suzuki Swift. Honourable mention to Ejector the toaster.
2010: Reveal the Shield Megatron; Walther P38 - not every day that Hasbro makes a gunformer that they can legally sell. Plus it's compatible with MP Jets!
2011: Wheelack; Mercedes Benz E550. Honourable mention to Soundwave, but the E550 is less attention-drawing than the SLS AMG.
2012: MP Lambor; Lamborghini Countach - yay, HasTak got the Lamborghini licence back!
2013: MP Streak; Datsun Fairlady 280Z
2014: MP Bumble; Volkswagen Beetle Type 1 - yay, HasTak got the VW licence back!
2015: Offroad; utility truck
2016: MP Ironhide; Nissan Cherry van
2017: Sqweeks; beat up Vespa motor-scooter
2018: Cogman; Aston Martin DB11 and the only Headmaster car with both a driver and passenger seat