Tank looks fantastic, congrats! Now I want to move to a soft water region...
T5 bulbs/fixtures are still good. Of course one day you will switch to LED, but until then, they will give you the most even lighting possible, plus you get a nice selection of bulbs and color temps and spectra.
Like you said, it comes down to personal preference, but if there was only one bulb, perhaps something fairly neutral like a Giesemann Midday would be a good choice. I've always had multi-bulb fixtures for that very reason, to get a mix of daylight (6500K), neutral (5000K) and plant grow (pink) bulbs with all their specific pro's and con's. Keep in mind plants don't really care as long as there is some minimum threshold that's satisfied.
And I don't think the increased or reduced or broken up light period has much to do with algae or plant growth... other things like intensity and nutrient availability play a bigger role. One of my tanks is on a 12 hour light period (10-10) and it is pretty much algae free compared to another tank (the big one) with a shorter, staggered light period.
In any case, you seem to keep track of parameters well, so if your changes don't work out as expected, you can further adjust them or go back to how you had it set up originally. If you don't like a 6000K bulb as it's only choice, switch it with a pink grow bulb and see what that does. Easy to do with T5 bulbs!