I've tried the Logitech Ultra Slim (not the tilting version) and the Zaggkeys cover and folio and the Clamcase Pros, all for iPad Air and iPad Mini.
I got fed up with the Zagg folios (in white) - the fake leather attracted too much dirt and I had too many missing keystrokes. The Zagg cover is very nice but with no back protection and having to pull out and rotate the iPad each time I wanted it folded back, was a chore. The Logitechs were good, but the keyboard was cramped.
Hands down, Clamcase Pro is easily the best. Heavier, yes, but the quality is top notch both in terms of build and keyboard (easily the best to type on with no double or missing key stokes, ever!). Only issue I have is the battery life isn't great, so it needs a charge every few days.
Anyway, here are some pics of the Clamcases with my WHITE iPad Mini and Air. The Air also undergoes a transformation into a black model, thanks to sticker boy, and the Air Clamcase becomes less white plastic and more brushed silver, looking much closer to a MBP.