It depends on what criteria, but here goes.
THe stand out one for me would be Everton and I am surprised they haven't been bought out yet. Maybe foriegn investors view Liverpool as the merseyside team and hence not bothered. They have been seeking investors for a while, have good support, good manager and wouldn't take that much in relative terms to buy them.
The ones that would cost mega money are Arsenal / Spurs, Manu is rumoured again with the Arabs.
Next you would probably go for best supported that wouldn't cost mega money, but in relative new ownership, Villa, Newcastle, Sunderland.
Then you have others that won't get massive support and will need hefty investment aswell, Bolton, Brum, Fulham.
The others maybe not enough upside in terms of possible support and maybe too much of a risk.
With the Eufa financial rules coming in at the end of the season, it favours the status quo, although these only apply to teams competing in Europe.