Transceiver every time if you can spare the dosh.
Not only useful in the (rare) circumstance of total radio failure (but make sure you've got a compatible headset adapter: you'll hear nowt over engine noise otherwise)), but also useful to get departure ATIS without cranking up your a/c avionics till you're ready.
For (relatively) small extra sum you can even get VOR frequencies as a NAV back up.
Depends really on the type of flying you're planning.
Cusco