We just used Humberto, he was excellent, very patient even with a group of seven from two families with two younger kids. I've asked for him again for next weeks trip.
We've had Mohammed, Darcy, Ian, Ronny, and a few others who's names I can't remember right now. They were ALL great - very personal, professional, and helpful. We never bother to request a specific driver.
We requested Brian and he was awesome! We started talking about the terrorist events, and as soon as we were approaching the gates to WDW, he said "Now enough, when we go through these gates, we can't talk about this stuff anymore!" It was super...we started talking about the parks, rides, etc...that really got us away from the gloom and doom and into the Disney magic!!
We have used Tiffany 4 times now. Each time I have been very pleased with our driver. I can't remember 2 drivers names but once we had Nausa and last time we had Jr. I would request either of them again in a heartbeat. But I can say that we have yet to get a driver that we requested but I still try
They're all good. My sister and I have had at least a half dozen different drivers from Tiffany, since we started going to WDW. and they all have been good. The only difference we have found is that some of them are more talkative then others. Sometimes this is good. Sometimes this is bad. Enjoy your ride.