Yale is in a rubbish location. I would pick Harvard/Stanford. This is how I see it - Harvard you make some sacrifices for undergrad for BIG long-term gains (namely the brand-name 'Harvard'). These sacrifices include worse social life as someone mentioned and being worked extremely hard. However I hear it is definitely possible to have a more social time if you want to go that route. Harvard's on the East Coast which is going to be closer to England, a fair bit colder, and probably a more familiar setting to what you are used to (if you're from England). Obviously there will be amazing professors there, who are available, but the problem is they will not all be that accessible. The opportunities once you leave though will be incredible.
You'll probably have a better time at Stanford. The name recognition isn't as good, but it is still AMAZING. I mean, pretty much everyone has heard of it, it will definitely catch employers' attention. You may even get a better undergrad education as they probably are more interested in undergrads than Harvard (although I'm not sure about this). It will be in the West Coast, so a more liberal feel, more laid-back, and also sunnier. The location is nice but probably quite boring (Palo Alto is supposed to be for rich old people), but San Francisco is reachable at the weekends. (I didn't like it much but that's probably just me). The campus is beautiful.. it's amazing. If you can I would definitely go visit both. I loved the architecture at both but you may prefer one over the other. Stanford may lean more towards the sciences but they are amazing across the board, they'll definitely be excellent at politics and economics, and I think they are amazing for English as well. Not sure about philosophy or history but I would imagine so. Basically your opportunities once you leave will still be excellent, so I guess it's more down to what you want out of your undergraduate experience and where you'd rather be, West Coast next to Palo Alto or East Coast next to Boston.