I HOPE the "correct" answer is a TT Professional 6200 because mine arrived this morning
My TT Go 740 is no longer supported so TT offered 25% off their price (obviously more than ebay) and included a free carry case. Perhaps there will be people around who would be willing to part with their TT account details if you want to try the same model (but you have to phone up and ask).
Whatever you buy, it will have good points and bad: we didn't really get on with our Garmin and I read recently that it is a PIA to change route once you're travelling.
Good luck with your choice - Gordon