Bluetooth GPS
Pro : no wires.
Con : have to remember to recharge the battery, more difficult to connect when you initialise, more expensive.
Bottom line : If you only use it in the car, get a wired one, find a good location for it and forget about it. Remember that your PDA will need to be docked for power anyway so it will need a cable.
If you want to use it for other applications (boat, walking, riding etc) then pay the extra & get btooth.
Note also that the TomTom bluetooth receiver is not the best or cheapest btooth receiver about.