Hmmm, I think both might be a little too blankety.
Do you mean IBO? I agree, that show has a lot of inconsistent character design, I like some and don't like others.
I've liked both styles though when done well, love Unicorn's classic-inspired look and Gundam 00's modern look.
Also, to be a bit fair to modern style, until IBO we hadn't had another "real" Gundam with modern design again since 00 so long ago.
AGE's designs were way too "kids show" style
Build Fighters is a total kids show
Reconguista was old-school in style thanks to the awesome Kenichi Yoshida (Eureka 7, Overman King Gainer), the show was a complete mess but visually it was pretty great
IBO's I think are kind of inconsistent, some are good some are really bad