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, 1XMarineland Doublebright, 2X Marineland 350 Magnum; 45 Gallon Tall, 96Watt AH Supply CF 6700K; 30 Gallon Long; Fluval F&P 2.0 36"/46W; 20 Gallon, 1X26W AH Supply LED kit; all with Press. CO2; (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?