Best buy for sat navs.

[enigma]

I want to buy my dad a sat nav for his birthday but didn't realise that there were so many choices and now my head hurts! From what I have seen, Tom Tom seems to be the best choice but is there a difference or do they all do more or less the same thing? What should I be looking for and are there any which have special features which wouldn't really be needed for everyday use? I feel that the speed camera alert and voice recognition sounds great but what is 2D & 3D mapping for? I'm so confused now (not being a driver) so can anyone please help?

[sense4all]

Tom Tom is easy to use - the only grief I have had was in a skinny London street surrounded by tall buildings. I had a mega expensive one ( Magellan ) and the new thin TT is easier to use and store etc. Mapping - either is good flat ( 2D ) or not. Speed camera alert is useful.

[enigma]

Thank you both for your answers, they have been very helpful. Much appreciated.