Well those are very different scenarios. If Prince of Wales, he could try for Anne of Brittany (Edward V was at one point engaged to her, and Brittany is a very nice dowry if you don't mind a probable conflict with France down the line). Alternatively, he could try to get a dispensation to marry his cousin Elizabeth of York, thus tying off that loose end and heading off a possible threat.
As an exile, he is a much less attractive groom, and will have to make do with what he can get (or wait until he reclaims his throne).
For Elisabeth of York, she will marry the Duke of Beja.