The Griot's G110 v2 and 7424XP are all very similar - don't let the specs fool you. The old Griot's had more power on paper than a PC, but bogged down far more easily. The new one rectifies that.
As for any of those vs. a Flex, it comes down to ease of use. I own and use both my 7424XP and Flex XC3401 quite a bit. Flex when I want power, PC when I want dead simplicity. You get a lot more cut/correction from a Flex, but it is a 2-hand machine that you really have to manage. The PC is super-easy to manage, but will take longer for polishing and doesn't have the very handy variable-speed trigger of the Flex.
If you're going to own one and you aren't doing a ton of detailing, I'd get the PC/Griot's/G110v2. If you don't mind managing the Flex, it is certainly the most powerful tool.