I say the second, with only one decal. It looks less cluttered. However those Hyundai decals are pretty cool, you could maybe put them on the painted side of your mirrors if you still wanted to use them (I know you would have to reorder them probably though.) That may be a stupid idea though....anyhow...the second one to answer your question lol
it's tough, and just like a baseball hat... you get a new hat and it's either gotta be prisitine or beaten to hell for it to look good. I think decals are like this too, cars look good (at least in my opinion) when they're pristine and clean or completely dumped with stickers like when you're sponsored I really like when cars have a whole bunch of sponsors down the side of the car but all of the colors match.
Everybody knows it's a Hyundai, so delete that one. The XD looks good, but will probably start to peel off and look like shit as you roll the window up and down. I like it, but would probably relocate it if it were mine. Just my 2 cents worth but who cares what I have to say.
EDIT: the best lookin XD logo I have seen thus far was over the 3rd brake light, or something like that. I think there was more to it - you know who you are.