I currently have the Garmin nuvi 660 but have also used TomTom and Mio (with rental cars when traveling in Europe). Regarding your specific questions:
City driving: You want to buy a more recent model with a newer GPS satellite receiver with higher sensitivity. Older receivers sometimes lose signal or get weak signal in obstructed areas, such as inside a parking garage, behind tall buildings or in snowy weather. Be careful with models that are older than 2 years but are often still sold.
Map support: The big companies have frequent map updates, maybe yearly. I don't know how often smaller companies (in the US) like Navigon and Mio have new maps. The value of these updates depends on whether you are in an area of constant construction and road changes.
Navigation quality: I think Garmin in the best, Magellan is a close second while TomTom is poor in this area. Go to a store with GPS on display and try out a few addresses you know, and see which brands give you the best routes. Also check how detailed the instructions are. For example Garmin tells you upon arrival, whether the place is on the right or left of the road. TomTom doesn't, so after traveling 100 miles, you are on your own for the last 100 feet :) Garmin is about as close to Yahoo maps as you can get.
Customer support: I've read that Magellan is terrible although I have no personal experience. TomTom is marginally OK. Garmin is great - knowledeable staff, no long wait.
Large screen: I like it. Easier to read map, and more importantly much easier to type addresses. On the smaller-screen models, I have to retype every 5th character because the keys are close to each other. Maybe you are not as clumsy :)
Links: I know you say no links, but read this one anyway: http://www.gpsmagazine.com/ . I find the reviews accurate, and the user comments insightful.
For your need and budget, I'd go with the Garmin nuvi 660 or 360. The 360 is almost the same but gives up the wide screen and FM transmitter (lets you play the GPS sound through the car FM radio). A budget model I might also look at is a Mio because it worked well for me in Europe, although I don't know how they do in the US.