For me Strobe Cream, the Fluidlines and the Disney TLCs, I know thats 3 BUT all of those three have completely changed my make-up. I look so much better with these things than without, I'm eternally gratfeul for finding the made-up me!
I expect MSFs would be on that list, but I'm yet to use one, I only just got into MAC recently and I'm nowhere near a counter and couldn't afford the extortionate ebay prices. Now maccosmetics.co.uk is live I'll be snapping up the next lot (whenever that may be)