The Batman Beyond version looks weird. For one, I always imagined BB to be more lean than muscular, and I always thought his costume had no expression or mouth - basically, I imagined him as a spiky, black-wearing Spider-man, which is pretty awesome. But I guess these are just mostly re-skins anyhow?
The old-man-batman version looks very retro, like the 1930s comics, cool stuff but the body looks bizarre. But then, the original Arkham Asylum Batman wasn't exactly a case study for average human body proportions.