ive owned a white car with white oem wheels. they werent too bad to keep clean but i really did have to keep up a weekly cleaning schedule, sometimes more often.
a word of caution when buying white aftermarket wheels. the paint they use isnt the same quality is whats found on your car. they tend to yellow pretty quickly on the less expensive brands. they will also absorb brake dust and stain brown as well. the powder coated wheels tend to last much longer. they are very hard to keep clean.
it might be best to find a wheel you like and then have them powder coated white with a powder clear over it. they will last significantly longer than painted wheels and theyll resist brake dust stains much better. also, keep the design simple. you dont want a complex design that you cant keep clean, itll make the wheels look 10x worse when a lot of crevasses are dirty.