My longest surviving fish so far are a pair of tank raised Ocellaris clownfish, who are turning 9 in August (my first marine fish too!). I also have a royal gramma who is almost as old... probably close to 8. These guys have survived brutal tank cleanings, hair algae epidemics, and several tank moves (one a 36 hour move from BC to Alberta).
The hardest fish to keep for me was my flame angel... cost me $100 and seemed to be doing great, but died a month later.
My three green chromis also died mysteriously after a month.