Since we're doing lists, sure, I'll add my stuff to the pile.
Autobot Headmaster Team: Love these guys together, and they're very cool to display.
Fort Max isn't that great a Titan, so I'm largely keeping him in my custom base mode, which makes me wish
Cerebros had a separate vehicle mode like Full-Tilt. Any fan modes out there? Anyway, out of all of them, I'd say
Highbrow is the weakest, for two nitpicky reasons: The guns and the rotor blades. I wish he could have landing gear without his guns, partly because the ones he has don't fit on Fort Max's runways. As for the blades, they make the transformation and posing of the figure more fiddly and cumbersome. Still, the helicopter mode is fantastic and the bot mode is still pretty good.
Chromedome I would normally call boring...not bad, just a little bland. However, thanks to character influence, he doesn't count as a single toy in my collection. He and
Rewind are always standing together on my shelf, to the point that the latter the sixth member of my Autobot Headmaster display. And as you guys have seen, I've had a ton of fun with them. Oh, and
Brainstorm is cool too, my preferred use of the Blurr mold, and
Hardhead is awesome. Love messing with his tank mode.
Decepticon Headmaster Team: These guys are pretty cool too, but due to the nature of beastformers they're more fiddly.
Mindwipe is not really the weakest in my mind, he and Skullcruncher are about tied. I wish I could mount Mindwipe's claw-thing directly to his forearm, using the peg makes it stick out too far. I find
Skullcruncher difficult to pose, not because of the loose joints, but just because it's hard to make him look right for some reason.
Weirdwolf is really good, I just wish the ankle tilts were easier to work with so I can plant his feet in more poses.
Galvatron and
Scourge: ...I feel bad for these guys. Cool design, cool alt-modes, okay transformations for the most part...they could both be the perfect figures of each character, but there are just all these small little things that ruin it. They're still not bad, but they're put down a peg in my mind because they're SO SLAGGIN' CLOSE to being perfect.
Blurr: He's nice, but not as good as Brainstorm. I wish I had the Takara paintjob, but the Hasbro one does still look okay in-hand. You could probably have the Takara in a running pose and have three Hasbro ones in the same pose behind him as speed after-images or whatever...oh, right, the figure! The Headmaster doesn't quite sit right because of the antenna, but it isn't too bad. The face is kinda off to me for some reason. And it annoys me that the gun won't peg in straight in vehicle mode like Brainstorm's does. Overall, a pretty nice figure, just needs a nicer paint job and doesn't quite live up to his moldmate.
Doublecross: I'm surprised that people dislike him so much, I think he's pretty nice. The hips are a bit trickly to get right in dragon mode, but once you get the hang of it it's pretty easy. My main nitpick is the guns, the detail that the bottom tabs are on prevent them from tabbing into the back or shoulders properly, instead always at a slant that leaves them less secure. I always forget to take the Headmaster out of the belly when I'm going to robot mode.
Hot Rod: One of my favorites. Great bot mode, great car mode, fun transformation. But the Headmaster one my copy can't fold his legs all the way. And for whatever reason, I usually set his guns aside when I mess with him or display him.
Triggerhappy: I honestly can't say anything that hasn't been said already. Great bot mode, one of the coolest starfighters I've ever seen in Transformers or otherwise, and an addicting transformation. Cannot wait to have Misfire and Slugslinger to go with him. Like Hot Rod however, I usually leave his handguns aside.
Bumblebee: Not too bad. I do dislike the cockpit, but it was kind necessary due to the transformation. My main nitpick is that the car mode just never seems to tab together right.
Brawn: Pretty decent on his own, but add his Headmaster and he becomes an awesome Pretender with a big Jeep-gun-thing.
Megatron: ...I don't like him as much as other people here. Which is fine, I still think he's great, he's just not perfect in my eyes. Certain things don't stay tabbed, the Headmaster is hard to get into the jet's cockpit, the tank seat doesn't really work, and the fusion cannon doesn't look right for some reason. Still, all the modes are cool, and my stickers have been holding up okay.
Optimus Prime: Sorta the inverse of Megatron, I don't hate him as much as others do. He's not as good as Megs, but the jet mode is pretty nice, and the truck mode is great once you get everything to line up. Stickers are peeling off, unfortunately.
For all intensive purposes, I am not longer active on Seibertron. If you want to find me, I'm most easily reached on Twitter, @sigma_magnus