I would avoid the Voyager Animated Starscream. I found him to be remarkably flawed with dropping off fingers and other annoyances. However the First Edition Prime version of Starscream is very nice indeedy.

I see that you have the JP release of Hot Rod there. If you feel extremely motivated, I would recommend getting the US release as well. It's coloured very differently, but I think also a bit hard to find.
I highly recommend hunting down the Studio Series Hot Rod and Kingdom Rodimus Prime (does you Rodding go to Rodimus as well?)
Since I mentioned that as well, some not Hot Rod Hotrods; Cybertron Excellon, and even the Armada powered up Hot Shot as well are fun toys. As for a different take, I really like the vehicle mode of Energon Deluxe Rodimus.
Naturally the Masterpiece Ver 2.0. Maaybe, but necessarily the Masterpiece 1.0 version with included Rodimus. I'll leave that up to you. I'm just gonna mention it exists.

Non Transforming wise there is also the revoltech Rodimus, which is kinda fun for the specific era of big-hands-figuoera art work style.

How do you feel about black Hot Rods?- Because they are a thing too. And TBH look pretty good most of the time.

I think Artfire is the smallest number.
G1, United, Masterpice and Generations Seletcs. They seem attainable.

AS for Favourite lines, Animated is of course way up there. I really dig the chunky space modes of Galaxy Force/Cybertron as #1. Helps that it had an dang amazing Optimus toy too. Oh and the Galaxy Force starscream is just fantastic! My fave look for Starscream.
That's all for now, it's almost lunch time