Wait, the horrible noise proctor Quinlan makes with his mouth is meant to be an English accent? As an English man, I take offence!
Anyway, From a combat perspective I've voted for MacCready. His default weapon has a terrible ROF and I find that he barely ever hits his mark. It's not too often he gets knocked over before he's done a single point of damage. His personality isn't too bad, but isn't that good either, though I think it's cool that they included him all grown up from FO3 and he gives one of the best companion perks.
Danse is my personal favourite. He seems to give more helpful dialogue than the others, and is probably the best in combat too. On top of that, he gives one of the better perks, has the highest carry weight, and I'm a total svcker for the BOS.