I can't pick just one. Different symbols on the suit make me think of different times in Batman’s history. Different artists can make different symbols look really cool. Some look great as symbols but look like crap on the bat suit.
I like the 98 one as a symbol when used alone but not on the suit. I'm also not crazy about the yellow.
The yellow was initially to draw attention. It would draw in the eyes and the idea was that it would act as a distraction, and hopefully prevent bullets being shot at his face, but at his chest. I agree though, it didn't look as great on the suit. I'm also a fan of the 2003 one.