Here are my E4 champions. I really loved the variety of pokemon in this gen, and a ton of them are feasible. In game, I use pokemon that i just think are cool, and quite a bit based old their designs.
Samurott: Love this guy so much!! His designs is awesome, and he is a tank!
Lilligant: Normally, I am not grass type user (I like them, but never seem to have a spot for them on my team). However, Quiver Dance + Petal Dance totally kicks butt.
Krokodile: Really cool ground-type that learns Outrage and his Earthquakes are super powerful.
Unfezant: Pretty bird. She's a female, because they look better than the weird head things males have. I just like flying types, and I almost always use the first flying types that are on Route 1
Haxorus: One of the coolest looking things ever. He is totally a beast
Reshiram: She has a really cool design, and she helped me out against N and Zekrom.
I absolutely loved this generation! Almost all the new pokemon were cool, and there was so much to do post game, and it was pretty easy to get pokemon up to level 100 with the Sport Domes