The 2X10 watt CFL's are certainly brighter both because they total 5 more watts and they are basically a T5 type bulb. (BTW, my tank has a glass canopy as well.) I can't grow most carpet grasses in this tank but the Helanthium tenellum (right foreground) does well with that amount of light. If you go with the T8 I would recommend adding the LED strip if it is in the 6500K spectrum you need for plant growth.
Roy 75 Gallon, 2X55W AH Supply CF 8800K, 1XFluval F&P 2.0 48"/59W, 2X Marineland 350 Magnum filters; 45 Gallon Tall, 96Watt AH Supply CF 6700K, 1X Marineland 350 Magnum filter; 30 Gallon Long; Fluval F&P 2.0 36"/46W, Marineland C-220 filter; 20 Gallon, 1X26W AH Supply LED kit, Marineland C-160 filter; all with Press. CO2 and (Calcined) Montmorillonite Clay Greater Seattle Aquarium Society (GSAS)
2 bulbs would put me at 34w isn't that too much for a non CO2 tank? 1 bulb at 17w would be perfect I think. Those fixtures are so pricey tho lol. Right now I'm looking at spending $45 on a T8 fixture and a bulb those fixtures alone are like $90 aren't they?