From my experience as a medical student:
-MRI: busy, FYs generally complain of tough rotas, parts of the hospitals new and shiny, childrens hospital bit is really good with everyone very friendly, lots of academic activity (e.g. research), teaching somewhat sporadic
-Salford: new, high performing hospital, everything is very very protocolic, clinical learning opportunities hard to come by although scheduled teaching always happens, spent lots of time here and the atmosphere here isn't great imho...this is the general med student opinion, FYs seem generally happy and I think the work-life balance is pretty good in F1, some specialities are limited in scope but good if you want to do neuro stuff
-Wythenshawe: not been very frequently but medical students and foundation doctors love it there, generally heard great things about teaching and the working environment there
-Bolton: a bit old and run down as hospitals go but FYs and med students like it here. Everyone is really nice and keen to teach...would definitely recommend. Close to motorway and Manchester...about 20-40 minutes commute from Manchester...of course this depends on where you live but I'd say from say Didsbury it'll take about 30-35 minutes to get there.
-Stepping hill: always very competitive to get into and everyone rates it highly although I have limited experience personally
-Wigan: A bit of an odd hospital as most of the outpatients is like 1.5 miles from the main hospital. As a med student, no one really care about you but junior doctors seem fairly happy. Difficult commute from Manchester...really good library though (surprisingly!)
-North Manchester: Busy! Overall atmosphere is good...FYs are generally happy here.
-Tameside: reputation not the best,I have little personal experience but people say often a bit disorganised
-Blackburn: I don't personally like the hospital (though not sure why!). Everyone is generally nice and FYs get lots of opportunities to do stuff. Busy!