Long Haul or Starscream. Of course if you're hanging for Leader Starscream then that will help sway you.
Demolishor is one of my favorite RotF figures, so I'd definitely recommend getting him. Long Haul is also an excellent toy. I'd skip Starscream and just wait for the Leader version, but Stratosphere is a neat toy.
Long Haul first and foremost. I haven't gotten Stratosphere or Mixmaster, but that's what I would want. Starscreams excellent, personally my favorite ROTF Voyager. However, there's the beautiful Leader version out soon, so you might want to wait for that. Still, on a budget, it's an excellent version.
If you're gonna pick up two voyagers...I say go for Long Haul and Demolisher, voyager Starscream is one of the best voaygers but you're gonna be picking up a Leader one so yeah. Hope I helped.
long haul.....i still don't know why i haven't picked him up yet....hell i haven't picked up a single ROTF transformer bigger than a deluxe.....that is a first LOL guess i am already burned out of movie figures
Starscream's really good, but if you don't mind waiting another year for the Leader one, you could skip it. Long Haul is great; one of my favorite RotF toys. Stratosphere is cool; lots of people don't like it but I think it's pretty neat. Those are the ones I'd suggest.
The only Voyagers I have from ROTF are Starscream and Demolishor. I like Demo. a little bit, but Starscream is a better toy. Buy him, unless you are waiting for the Leader. I don't have them (yet), but I've heard good things about Long Haul and the Voyager Megs.
THIS completely (minus the Stratosphere part cuz I passed on him) but Demolishor is a lot of fun. He's on of my favs. Although, maybe you want to wait for the hasbro release of the silver version. But hands down. get Long Haul. Great Transform. Not too hard, not too easy... just PERFECT.
I finally got Long Haul (never once seen him on a shelf, had to go HTS and he was worth the hype. I heartily recommend him. Get Starscream too, the two are pretty close to in-scale and make a good pair of servants for Megatron (one is big, dumb, and loyal and the other is...Starscream). Then get Leader Starscream anyway when he's out. I usually begrudge getting multiple versions of a character but I'm totally doing this.
Of those on your list, Long Haul is the best by far in my opinion. Good looking vehicle mode, great robot mode with lots of articulation, good proportions, and alternate ways to pose his various pieces. Just a very strong figure overall. Starscream would be my second choice. He has an awesome transformation, but a few minor issues. His hands hang off in jet mode, they have no articulation, and his arms pose a bit funny.