It's a mixed bag really, imo you should choose on a per character basis.

Two obvious ones where Hasbro wins are:
-Cliffjumper (JPN release is a strange orange, stickers look terrible)
-Ratchet (JPN release stickers crumple around collar, lacking red on legs)

One thing I will say is that Takara Skywarp and Megatron are the most fun I've had with Transformers for as long as I can remember. It took 30 minutes + putting the Micron's together and adding all the stickers (which are really nice quality and go on with nary a crumple in sight). The little jewels are a particularly nice feature on the Micron's, I love putting the faction stickers on em then covering it with the translucent jewel. So cool. Overall you get a great feeling of accomplishment after building and stickering up the JPN toys, I can't wait to get more of 'em!