Depends a lot on what kind of fish you keep. I have a bunch of GE Aqua Rays 9325k flourescent bulbs over my big tank because they are just amazing at bringing out the red/orange/pink end of the spectrum, but they don't have a pinkish hue at all like some other 9325s apparently do (Compact Flourescents I guess). I have a lot of reddish fish in that tank (and a silver aro, whose fins and scales just look great under it too). If you've got blue fish, a 50/50 and 10000k dual bulb setup looks great without being too blue (I have this over my african cichlid tank with a bunch of demasoni)... and there are a bunch of other options as well.
Unless the focus of your tank is plants, just stick within the general guidelines for WPG for keeping the ones you have healthy and just choose whatever fits your budget/the available space/the colors of your fish. You can put together your own flourescent fixtures on the cheap from Home Depot too so unless it's a space crunch or you need a ton of watts that's a nice easy way to go.