Really depends on what you mean with webapp... if you say hostgator I suppose you are talking about a PHP website. It's been a long time since I last used one of those services, I now host everything on my Rackspace VPS. For ~15$ each month I have a VPS all for me wich I can manage as I want.
Otherway I heard a lot of people saying that Heroku (Ruby, Node.js, Clojure, Java, Python, and Scala)is very good. Or Google App Engine (Java, Python, Go)
I like linode - $20 a month you get your own machine, service is great, docs are too. All I can say is maybe its too much for what you want. You also probably need to know what you're doing but as said the docs are really good so I think even total newbies would have no problems with copy/paste.
I've had a good experience with Godaddy, there was a lot of bad press a few months ago, but I've had no serious problems in 4 years. I have 5 or 6 different sites hosted with them.
