Thinking of buying just two...

[GoktimusPrime]

I don't own Blurr (the concept of the toy doesn't interest me) nor have I ever handled the mould IRL, so I'd say if people who have both are saying that Blurr is the better of the pair then it seems like sound advice.

I'm assuming that you don't know of any other collectors near you that might own the toy for you to try before you buy?

[Ode to a Grasshopper]

Personally, I'd expand your list and get the old 1987 Headmaster crew - Chromedome, Hardhead, Brainstorm, Highbrow, and Weirdwolf/Wolfwire, Mindwipe, and Skullsmasher/cruncher. Having the full set of reimagined Headmasters would be pretty cool IMO.

If you're only after 2, though, Sixshot would be a good standalone figure. Though of course, Trypticon is supposed to be released under the TR line too...
For an Autobot, it sort of depends. If you're a Headmasters (as in the Japanese TV series) fan, Chromedome. For a good standalone figure who could work well with Sixshot, maybe Powermaster Optimus Prime. For a good standalone figure who has good feedback, I'd go for Wheelie.

[UltraMarginal]

You might also want to wait a while for the newer waves to be released. traditionally the later waves of a toy line are better toys, whether because the designers have settled into the play pattern a bit more or if they've had more time to design the toy.

I only have 2 myself at the moment. hardhead, it's a decent figure, not complex but interesting enough.

Skullsmasher is a very simple transformation and the head and tail don't really do anything. the bot mode is fine, the Croc/Gator alt mode has a very nice aesthetic and shape. it's not just a straight croc, it curves up at the front shoulders to lift the torso. the back legs don't do much. Its not very stable.

The little Titan heads with their teeny vehicles are very simple, I only have 1 and I'm so unimpressed I can't remember it's name. I'd be happier with them if the were $5

[UltimateGalvatron]

Personally, I'd expand your list and get the old 1987 Headmaster crew - Chromedome, Hardhead, Brainstorm, Highbrow, and Weirdwolf/Wolfwire, Mindwipe, and Skullsmasher/cruncher. Having the full set of reimagined Headmasters would be pretty cool IMO.

Yeah that isn't a bad idea, I just don't wanna get hooked and blow all my money, LOL. Maybe if I set myself a goal I can stick to that...