In my opinion, i think the designs in the 6th gen are great. Okay, in order:
1) the goomy line (goomy, sligoo, goodra). How could you not love this line? Come on, first it's a blob of goo, then a gooey snail, then the cutest dragon type ever. I am a proud owner of a shiny goomy; now a shiny goodra, which hatched after 454 eggs. Goodra is officially my favourite pokemon. I think it resembles reshiram a lot.
xerneas is the life pokemon. It's a magical, colourful-horned, fairy type deer with legs that resemble swords (kind of). I'm quite fond of fairy types right now, i mean, come on, they resist those pesky dragon types and just completely own them. I bet competitive battling will be very different in this gen with the brand new fairies and mega-evolutions. Xerneas has a unique design for a legendary. Most of them fly or float, it's nice to see a change.
this naughty panda isn't quite as cute as his pre-evolution, pancham. Again, he has a unique design, unlike any other pokemon. I'm also madly in love with panda's. It's a fighting-dark type (not the best combo in my opinion), but it sure packs a punch. It can learn a variety of moves, like surf and dragon claw. It seems quite a friendly pokemon, as the pokedex states; "it won't put up with bullying". This panda may be intimidating on the outside, but on the inside he's very caring.
4) the amaura line
amaura is a fossil pokemon (sail fossil). It's the cutest fossil pokemon ever! Big blue eyes, tiny mouth, small head. It's also dotted with jewels! What a classy pokemon! Aurorus is not so cute, but very majestic. It's a rock-ice type (oh, that typing! ). I've tried it a few times, but it just cripples. It can't take many hits. The only reason i like it is purely based on design. In my opinion, if you're looking for a member of a team, i suggest not going for aurorus.
5) meowstic or sylveon
meowstic isn't very unique, considering how many cat pokemon are out there. The thing that first struck me was that it looks different depending on gender. The boy focuses on supporting moves, while the girl focuses on offensive moves. It also has a nice ability, competitive; which raises it's already great sp. Atk stat when another stat is lowered. It's decent for competitive battling, but i find that it doesn't stay up too long. Sylveon. Just look at it! Another eeveelution. Surprisingly it's quite defensive. It can take a few hits, and can give a good few punches! If you run draining kiss on it, it stays up for a long time. This little ribbon pokemon just destroys dragons.