I have a 3.5" widescreen. 205W Garmin I believe. No traffic but I have an iphone for that. No map updates but it is still good 5+ years after I got it for most every road I take, and I travel a LOT. If you travel a lot and want to take it by air, the GPS in a protective box can become an unwieldy size if the screen is too big. Ive never felt the need for a huge screen and its associated cost.
If I had my choice, I would use one that spoke the actual street names, which mine doesnt, and which has better clarity on how the lanes split off in areas where there are a lot of lanes going in each direction.
The one time I saw a GPS with traffic and ads, it seemed to show a lot of red lobsters and olive gardens...