When I saw the first answers, I thought there was an open war between the two cities!!
There is! Manchester and Liverpool are ancient foes - Scousers hate Mancs and vice versa. A bit like Glasgow Vs Edinburgh, Newcastle Vs Sunderland, etc. Normally this only manifests itself as good humoured banter, though.
Having been brought up in one and lived in 'tother, I can say that they are both unattractive sh!tholes, but on the flip side, they both have alot to offer - much money was poured into Manchester in the 90s, just as much money is being poured into Liverpool now. Both have some very nice places to live and socialise. Both have more than their fair share of theiving chavs - On balance, Manchester is slightly worse in this respect, but their is not much in it. What would pip it for me, bearing in mind you would probably want to live somewhere outlying and commute, is that Manchester's traffic problems are far, far worse than Liverpool's - By accident or design, Liverpool is far easier to get around, there being usually several ways of getting from A to B.
But for heaven's sake, don't under any circumstances live anywhere near the airport (Speke) - that area truly is a sh!thole!
16B