I recommend TomTom. I am on my second one as my first was nicked from my car. Very intuitive to use, it has a big instruction book which I've never needed to read.
It has only a few sites in UK (Caravan clb only) and in France but has loads in Spain for some reason.
I have also downloaded the free Aires in France which has proved very useful the last few weeks.
It uses a SD card, cheap and sold evrywhere, which you can replace with a bigger one so you can add in all the good places you find so you can find them again!
