I have them both and I do like Thundercracker better. I can't wait for a US Skywarp and any other repaints this mold brings!
I don't have Starscream, but I've got Thundercracker. It's definitely a mold worth owning, but at the same time it's not perfect. I do plan on getting the Skywarp repaint of it.
I got Thundercracker first and found him really awesome. I then got Starscream recently, and might like TC a bit more because I think the colors look great. It's pretty amazing how they were able to capture the proportions and accuracy in both modes at that size, and it's a fun figure with lots of pose ability too! The only thing I don't care a whole lot for about Starscream is that he looks so out of scale as a Deluxe when with any of the other figures.
It's one of the best movie dlx molds imo. It strikes a very nice balance between Cgi accuracy, robot vs altmode & articulation. TC's got the better colors though because Starscream's clavicle parts are made out of the same grey plastic as the shoulder hinges, while TC has that black & light grey respectively..which results into better color blocking. In short..I've got like 10 DOTM TC's ; should be pretty indicative about how much I like it.
I have both Starscream as well as Thundercracker, and I like both, but I like TC's color scheme better. I really hope that if they produce a Skywarp in the U.S. market that they use the same F-22 mold, and not something different like they did with Air Raid.
He's a very cool and poseable little mold and is second only to the Leader/MP figure, I think. Definitely worth it; even his mech tech weapon, which I hated at first, I warmed up to eventually for how fun and neat it is. I have three Deluxe Starscreams, all of them custom painted -- one is flat gray but still has an understated F-22 prototype appeal, one is dark yet shiny silver for a very cool Deep Space SS motif, and the last one sports a similar camo paint scheme as the MP-M01 SS. (In the end, the tattoos don't really do anything for me.) I love them all! I also have two Thundercrackers. The Deluxe mold goes very well with their Classics/Universe/Henkei counterparts in terms of scale, and is how I plan to display them in alt mode (once my wife gifts me with the Japanese exclusive Skywarp). The dark silver one I plan to mod out with Fakebusker's Shapeways weapon add-ons and pose with Revoltech Movie Prime since they're so similar in size. The flat gray SS I currently have displayed flying in my Cyberverse collection (all alt modes) since I think the Deluxe scale works better than Legion-class SS (who's too small). Definitely a versatile and awesome mold, IMHO!