I'm no expert so use this info as a general guide.
Popular power tools are:
Random orbital - good, better, best = Porter Cable, UDM, Flex. The Festool would probably fit in between the UDM and the Flex.
Rotary - all seem good but require more skill and popular brands are Makita, Hitachi, Dewalt, Metabo. The Dewalt is reported as heavier than most, the Metabo lighter than most.
Those new to detailing often start with a Random Orbital and progress to a rotary as a later step. Random orbital machines make it difficult to damage paint. Not so with an improperly used rotary.
Price wise, a used PC would be the most reasonable and a good starting point. I'm thinking quite a few are thinking about selling their PCs and upgrading to a Flex, so deals are possible.
Others will jump in with tools/brands I've missed.
-John C.