Lately I've been shipping Mac/Stella because I watched "What You See Is What You See" and the Scary Oatmeal Lady, well... she scared me so much that I can't see Mac dating anyone else but Stella. They have such good chemistry, and it's obvious that Stella can get away with stuff the other CSI's can't because they know each other so well.
But on the other hand, Mac and Lindsay have good chemistry too. They work well together, and I'm certain if they were together outside of work they'd get along fine. Plus they're just adorable. So, if they became a couple, I wouldn't object. I remember writing a fic for the pairing a while ago. It was good, if I do say so myself.