I've heard many claims about the analogue component quality of ATI MFG'd cards being noticeably higher than pre gf4 nvidia cards, but in a side by side comparison I didn't notice any difference. On the other hand, matrox IS noticeably better than ati or nvidia. If you're on a budget and aren't gaming, I'd go with a lower end matrox.
One thing to note with monitors, is that purchasing from a local vendor (like bestbuy) that will pricematch will be loads better than just ordering from the cheapest place on the net. When it comes to higher end monitors (like $300-600 range), the quality of each unit can vary a lot. My 19" trinitron FD still has a small convergence issue on the upper left hand side, but warranty service states that I have to pay for shipping (around $90) if I want them to RMA or service it. For a $300 monitor, it just isn't worth it.