Hazard would fit at United but they already have 3 great wingers who would all want to play as much as possible, think they'll just go for a playmaking centre mid and maybe a backup for Evra and that's it.
City are dying for wingers but it's not in Mancini's tactics unless it's a 'plan B', which I don't think Hazard would accept as other clubs would make him first choice. Johnson and Milner as two examples hardly even play as true wingers for us anymore and Hazard would probably end up the same, really wouldn't want to see his skill and creativity bottled up a bit with City's tactics.
Spurs would be a great fit, Bale and Hazard interchanging on the wings would make for a scary attack, would give them 3 top quality wingers as well with Lennon thrown in and maybe Dos Santos getting a game or two eventually.
Of course this means he'll end up at Newcastle miraculously for 6mil or so when they make top 4 so it doesn't matter anyway.