I like Bare Minerals powder foundation - the trial kit for £45 is good value. It's very light and I found I got less spots using it.
But I'm now about to try Clarins Skin illusion foundation after really liking a magazine sample - feels really sheer and light.
If you have time go and try some. Say you want to see how they last the day on your skin before you buy or ask for a sample. Any sales woman worth her commission should see sense and either slap some on you or proffer a sample
I am currently wearing clinique superfit but find it disappears through the day, but am on maternity leave so usually get slimed by my 7 month old before then and it's not worth the effort to reapply.