I chose white gold simply because I wanted a diamond wedding band and the ones in platinum were twice the price and way out of my price range.
Also, since I have 12 diamonds in it, the only metal to be seen is underneath my finger and no-one would notice it.
Same with my engagement ring - no-one really notices the metal as it's underneath.
Whilst saying that though, I have to get them re-dipped once a year. I seem to have the body chemistry that's the worst for white gold. My husband on the other hand has a plain white gold band that still looks great.
It only takes a week, and it costs very little, but it's still a bit of a pain to have to get it done! At least it gets polished up at the same time. They really do come out looking just like the day you bought them. You fall in love with them all over again.
I'm really glad that since so little of the metal is visible, I can let it go for a good long time. Like, right now the underneath of my wedding ring is definately yellow-tinged, but nobody knows but me. I'll have to bite the bullet in the next couple of months though.
If you're getting a plain band I'd recommend platinum. Yeah, it scratches quite a lot, but nobody but you will really notice. Who's gonna get that close to scrutinise it? But if it goes yellow it will be noticeable and you'll have to be on the ball with getting it re-dipped.