No one makes 9325k T5HO bulbs, which is what you need for Teks.
IMO you don't need 6 bulbs, 4 should be a gracious plenty- especially with Teks.
Giesemann does make the top-of-the-line T5HO bulb ATM, so I'd go with those for sure.
Most common choices would be 6k, 8k, 10k, and AquaFlora. If it were my fixture, I'd get all of them to mix and match and see which ones you like best. All of them are great for plant growth; so it boils down to which ones you think LOOK the best.
I'm personally about to add a Giesemann AquaFlora bulb to my fixture (if it ever gets here...); this is a pink bulb that's supposed to be awesome for red plants.