I use my table saw with a sled for most cuts. To be honest though I don't worry much about rails or stiles being cuts exactly square....as long as they're close enough it's fine. When I cope my rails I remove about 1/32" of material on each end, this ensures that I get a full profile cut, and that they are dead on square. Stiles don't need to be square either as I'm going to do a finish cut on the door after glue up. That's when it needs to be dead square and the table saw does a nice job of it.
good luck,
JeffD