It is different with every source I have looked at... I try to keep mine around 92-93 range. I have asked several BP breeders as well. They all said 92-93 is best if you can keep it in that narrow of a margin... otherwise 90-95. This is for UTH temps for racks with no basking bulb as the bulbs aren't required as long as you have the temp correct.
That's what I've always been told, as well. Tank seems to like it!