When I was a kid, my "most fun to TF" toys were the insanely simple ones, like Scamper, the little car that came with Metroplex. It wasn't because I really liked simple toys, but because I could transform them in 'real time', as fast if not faster than they did in the shows.

 

most fun: Classics Prime/Universe Cyclonus
least fun: Alt Prime/MP Megatron

 

Most fun: Masterpiece Megatron, though also the most difficult, I actually like his transformation, a perfect updating of his G1 transformation. Only real downside is that it can be a bit scary to do, I mean, who wants to break a $100 figure? The Animated line as a whole is also quite fun.

Least fun: Marvel Crossovers Venom, it just can be a bit frustrating at times when it really shouldn't be. And the end result isn't quite satisfying enough to justify it.

 

I really like all the Animated toys.

The Movie toys suck.

 

I'm gonna go against the crowd here and say I like Alternators transformations. I love how complex the transformations are, yet they are not rocket science. Just takes some practice. If done right, it doesn't take too long on some characters either. Jazz is actually one of the easier transformations imo.

My least favorite Transformer to transform would have to be TFTM leader class Megatron. On top of how shitty the toy is in general, getting the legs just right under his wings is a bitch.

 

Most fun: Animated.

Least fun: Movie Blackout and Megatron.

 

most fun - mp-4, most animated figures, universe cyclonus, hound (and all universe legends  )

least fun - mp megs, universe galvatron, movie concept camaro bumblebee

 

Most fun... I'm gonna give to Classics Mirage. Man, I have NEVER seen so wrong about a toy I saw as a prototype first. I thought he was ugly and just bad... he's probably my favorite TF in my collection now.

Least fun? Probably Alt. Grimlock. I don't have that mold anymore, though, so as far as what I have, I'm not sure...... Maybe Animated Starscream, but I'll have to give it more thought.

 

Movie Barricade really gets to it too, 'cos its just frustratin' to try and squeeze and wrestle the parts just right at the end... didn't even get him totally transformed for his latest appearance in my comic.

 

Yes!

Most Fun: I love Cybertron Primus and his key gimmicks for some reason. Alternators Hound is also a favorite. And I absolutely love the G1 minibots.

Least Fun: For official Transformers I would have to say the Wal-Mart Exclusive Masterpiece Starscream. It's not difficult, but I just get really nervous when I transform him. For the non-Transformers characters, I would say Death Star Darth Vader is incredibly frustrating. I changed him into the Death Star when I first bought him and haven't built up the nerve to try it all over again since!

 

BT Wheeljack/Grimlock is a tiresome bugger, from bot mode to car mode, but I find him the exception to the rule - otherwise never had a problem transforming BTs.

Ones like G1 Soundwave, Prime or Bumblebee were always the most fun as a kid, just because you could get them in bot mode in the time it took to make the transforming noise..

 

Most fun: Pretty much all my G1 bots. I enjoy the simple transformations, it makes fiddling with them a breeze.

Least Fun: Optimal Optimus and Fire Convoy. I just don't enjoy transforming these two at all. It's funny because these are my two favorite Optimus figures.

 

That pretty much describes my favorite toy to transform.

Least - I would say it would be movie Megatron.

 

Least fun is Alternators Grimlock... those damn arms and torso when transforming back to Mustang are a bitch for me...

Most fun? I don't know really...

 

one of the most fun to transform is BM obsidian. a couple that are a pain are classics ironhide because all he parts are hard to fit together. classics sideswipe because once you learn how to you forget. and the worst is camaro concept bumblebee because the second time you try to transform it into bot mode you strip the gears and then you have action master movie bumblebee.