Castle Irwell - probably has the best social life but.. I wouldn't call it clean haha. Irwell has parties a lot and so if you're into that scene and don't care about the cleanliness of the place then you'll be fine. I know of people who often have nights where it's too loud to sleep properly and people seem to set the fire alarms off a lot.. So ear plugs might also be a good investment.
John Lester/Eddie Colman - this is where I live, and it's pretty awesome. It has a good social side because there are rooms downstairs where people can chill, and during freshers week etc there was always a lot of people downstairs recruiting people to go out drinking/clubbing. It's not as noisy as Castle Irwell either so you can sleep easy. The walls seem pretty thick; i can't really hear anyone from the neighbouring rooms. It's also awesome because although not on campus, you can leave 10mins before lecture starts and still get there on time.
Horlock - on campus. haven't been inside, but I think people get stuff stolen quite a lot. it also looks.. not that great. so you might wanna visit this one before choosing it.
Constantine - i don't know much about this one.. It's on-campus and ensuite so that'd be pretty sweet. It's close to Horlock though so idk how much that influences it. But I can see it being quieter.
Bramall - don't know much about this one either. Seems similar to JL/EC but is the opposite direction from uni. I think it's quieter than JL though. And when I visited it, it looked pretty bad.
Dirty etc. JL/EC are new so are clean and modern but Bramall looked like it was crumbling haha.
IQ - expensive but looks really awesome and has a good social life. If you can afford it and don't mind the extra walking to the uni it's probably a good place to go.
I think I covered them all... Feel free to quote or inbox me if you need anything else.
About the accommodation - look above.
By student life do you mean specifically the night life etc? How can it be dead?! Salford is on the outskirts of Manchester which is one of the best places for a night out...
Salford has a couple of decent pubs but for proper nights out we always get the train. It's literally only 3-4minutes train journey and the trains to Manchester are really frequent. Manc has awesome clubs and stuff so it makes for a great night out. Get a taxi home and split the cost between your friends and it isn't expensive.
Feel free to inbox/quote me if you want to know anything else.