For most jewelry white gold is going to do the same job as platinum. Platinum is heavier and a bit more durable. It can be fabricated better when making complex items than gold, but simple solitaire rings generally are not made in a way that platinum is totally required. Platinum is easier to hand engrave, but there is plenty of engraved white gold jewelery, too.
When not rhodium plated, white gold is a bit yellowish and platinum is more grayish in color. Rhodium on a ring is a short term plating anyway so it is only an intial "look".
People will almost always recommend platinum, if you can afford it. I basically agree, but I wear a nice 14kt white gold diamond ring every day and it is light weight and looks just fine....So the answer is really a matter of choice in most cases.