I can't suggest a brand as I don't have T5 personally, but from seeing others with a 6x fixture, they went with 3 10k bulbs and 3 actinic. With 5 bulbs tho, I'd probably do 2 10K bulbs, a 50/50 bulb, a 420 nm actinic and a 460 nm actinic so you have the full spectrum covered nicely.
Take my advice with a huge grain of salt tho as I don't have these types of lights.