I would probably say change them out, bulbs are a tricky thing to deal with simply because if you're seeing the light each day you don't notice changes. There are so many factors to tie in, from ballast to brand of bulbs, to how long you fire them that can determine when you should replace them. Most people swap them out anywhere from 6 months to 1 year though.
I don't really have a preference as far as company, many people love the radium 20000k bulbs, I might give one of those a try over the summer, but they are a bit on the pricier end of the spectrum. It all depends upon your preference for what you see, Reeflux 10k bulbs are great for a good amount of light, and a fairly cheap price, if you have a double ended bulb setup quite a few people like the Phoenix 14k bulbs, also fairly inexpensive. But it depends what you want to see out of your tank.
