Well, what are you planning on doing with your machine? Cost aside, the Pegasos or A1 will ensure that you're set for the future, whereas a PC with UAE/Amithlon will give you the fastest access of Classic Amiga apps. PCs are available in some really cool, really small cases, which is always fun. You could also do the same when the MicroA1 comes to market. Also bear in mind that you'll lose direct access to older games/apps with a Peg/A1 (UAE will be needed), but an emulated system should be able to handle them directly.
It's your call, though - what do you want? Older stuff only faster, or newer stuff?