Assuming you mean for battling, but even there my influence is cuteness.
Although, I'd have a different list if we were just going for adorable.
1. Wistala - Tiny Emerald Whelpling - My favorite companion pet, and my go to for pet battles. Cute as heck, and survivable with either dragon or magic attack.
2. Franz - Mechanical Pandaren Dragonling - As an engineer and a fan of whelplings, this is a no brainer. Plus it's the best vs magic types.
3. Mini Tyrael - He's rockin' both on and off the battlefield.
4. Gu Gu - Panda Cub - He's got adorable and bear-bashing critter-smashing covered.
5. Tari - Stunted Direhorn - honestly, I didn't really have a good 5th slot, but this little cutie appears in at least one of my standard teams, so there ya go. 8)