I'm currently looking for a multi fx pedal, and so far the ones which are within my price range are the Digitech RP500, Vox Tonelab EX, Korg AX3000 and Line 6 POD XT Live..

Any clue as to which is the better of the 4? I'm looking for good feel and tone, as usual, synth effects and I want a whammy which could extend to 2 octaves (+/-) hopefully. Also, ease of use, and to be able to blend the fx together..

Thanks guys.

P.S.: I play through a Cube 30x, so the mfx would work alright with that??
I know this might now be what you want to hear but maybe it would be best if you sold your amp and saved up the money you were going to use for the pedal and either bought some sort of vypyr or maybe save up for a small tube amp combo?
idk these are just things to think about if tone if the most important to you rather crazy effects.
Vox Tonelab is really pretty good, the tube inside gives it an almost tube like tone, but if you save up for a bit longer you can get the Line 6 PodHD300 which is a very powerful mfx pedal
If you want the mfx unit to sound it's best, than I would save up for a new amp. I use my rp355 through my cube and it sounds fine, but it could be little better.

I highly recommend the digitech rp series. I have the rp355 and it's great.
Guitars: Fender FSR Standard Strat, Squire Affinity Strat, Epiphone Nighthawk
Amps: Vox AC15C1, Roland Cube 15x, Peavey KB-1
Pedals: Digitech RP355, HD500, Joyo AC-Tone, EHX Soul Food