When I passed I toyed with the idea of one of the cheaper ones, but in the end ended up investing in the TomTom 6250 Pro with lifetime traffic and maps. I purchased directly from TomTom and managed to get a code for discount so cost just over £300 in total.
I firmly believe you get what you pay for with anything in life. Buy cheap, buy twice. I’ve used it everyday, even when I know where I am going it’s excellent for mobile speed cameras and live traffic. You can also hook your phone up to it to receive calls and text messages but I have personally not really bothered with that.