I have fallen out of love with fat quarters. As someone said...they're often wonky or cut so far off grain you're left with a scrap after straightening up. Plus if you fall in love with a fabric, Murphy's law dictates that the piece you get will NOT have the selvedge that actually has the manufacturer's info. So for me, half-yards is the minimum I'll buy; I prefer a yard.
I would trust Connecting Threads though. I haven't bought from Keepsake but have heard good things.
Watch out for FQ's at Joann's, though...some are decent quality but in my experience the vast majority of the FQ's there are terrible - very thin, meshy weaves that you can see right through. Joann's gets a lot of hate but I like the store, generally speaking...but I agree with the haters when it comes to their FQ's.