If you want to use a phone in US/Canada then quad-band is beneficial, though if you're only travelling to major cities then you can probably get away with a tri-band phone.
If you want to use a phone in Japan/Sout Korea then 3G (UMTS) is needed.
Out of the ones you've listed, the V3x is probably the more suitable since it's tri-band and 3G.
The only quad-band and 3G phones I've seen are the Nokia E61 and N80, but it really depends on where you're intending to travel as to whether you need that much connectivity.