That Aqeon is probably the same or similar to what came in the kit. Topfin is the store brand, but manufactured by other companies. My guess is that it is Aqueon since they carry a lot from them, though I guess it could be Marineland or some other company. Aqueon and Coralife are the same company as well (subsidiaries of Central Garden and Pet), Coralife may be 'higher end', but they may be the same as well. I have had a Coralife bulb in the past and it was good.
I tried that Aqueon in 18" length, it was very dim. I don't know if they are all like that or if I had a defective one. Returned it and bought (at Petco) a ZooMed mentioned by Byron, which is much better. Mine is the FloraSun, which does have a slight purple tint, so if you don't like that go with the fuller spectrum.
The best T8 bulb I've had was GE. I think its called Plant and Aquarium, though probably the same as a general 6500K or so bulb you could get at the hardware store, nice bright white light and great plant growth as well.