Here's the ones I own, and my reviews of them:
MP-01 LAST SHOT Optimus Prime: He's HUGE and HEAVY. Diecast everywhere, big like a supreme class, is fun and easy to transform, and the robot mode is PERFECT. His only fault is a vehicle mode that is rather meh... If you have 150$ to spend, get it. He's worth it and he's pretty sturdy, unless you have ham-hands.
Masterpiece Starscream (G1 colors): So far, my favorite MP figure. I don't understand what are your "breakage" issues with him. He feel solid and sturdy. Only some top fins pop-off in transformation and they pop right back in. The jet mode is 100% perfect, but the robot mode have them annoying wing-flaps on his hips. But just pop them off from the ball-joint and attach them to his legs and voila, a perfect robot mode! Transformation is intuitive and fun.
Masterpiece Starscream Ghost Version: Same as above, but clear.
I love them both so much, I invested a small fortune to display them properly:

MP seekers are fun and great. Get any versions. They are worth it a lot. They ARE the ones I transformed multiple times without troubles.
MP Rodimus (Hasbro). He's a bad figure. He look nice in robot mode but that's it. He's fiddly and complicated to transform. I'm always affraid to break something. His hands are badly designed wich make him holding his weapons a near impossible task. His vehicle mode look unfinished because the panels don't want to allign properly. Get Rodimus only if you find him cheap in store.
I don't know if that one count, but I'll include him anyway:
Costco Exclusive GOLD leader Spec-Ops Bumblebee: Perfect robot? Check. Perfect vehicle? Check. Fun transformation? Check. Loaded with light-and-sounds? Check and check. He have a very nice metallic finish compared to the regular version. He also come with a legend Mudflap and a VERY SHINY legend GOLDEN Bumblebee! That's a 70$ well spendt here.
"Movie Masterpiece" of them exist, but if you don't want to spend 100$ extra for a shiny paint job, these figures are just perfect and fun:
HftD Leader Starscream, DotM Leader Sentinel Prime, DotM Leader Ironhide. Some like RotF or HftD Leader Optimus Prime (also Buster and Wingblade) but he's a bitch to transform.