I have been fighting them with ladybugs and soap spray which is working great in my tent grow because the door is mostly closed and the environment must be perfect for the ladybugs because they are humping and breeding like rabbits with little tiny ladybugs everywhere.
However, with my outdoor grow and my indoor grow they are not working as well. I get most of them but now and then I wake up to a plant that seems to have been infested overnight.
I never use ANY kind of pesticide so bugs are a real challenge to me. Fortunately, aphids are not the worse.
@Ringodoggie Watch out using the soap spray and te ladybirds, the soap spray can kill them too. Thats the thing with bioligical control, (which I am a big fan of) its all or nothing, when you go down that route you pretty much have abandon all the sprays, whether they be organic or not. Where you find them your can just wipe them off, its wont keep them at bay long, but reduces the numbers ready for the ladybirds. Another good biological control is encarisa wasp. A micro wasp (most wasps are tiny).
I work in the in nursery trade (sort of) and we have found encarsia pretty effective. By the way, with ladybirds is more the larvae than the adults that eat the aphids.
Good luck, like you say, there are far worse pests than whitefly.