T12 "regular" fluorescent have very low lumen/watt - Personally I use T8 because lumen/watt is similar to T5, but the lamps last longer and are marginally cheaper, also the T8 ballast can be found used on Ebay for very cheap compared to T5, and you can simply rewire your T12 fixture with a new ballast and not have to buy the whole thing. - or even buy a cheap shoplight T12 fixture and throw the ballast out - also I use metal halide lighting and HPS lighting, and with proper choice these are also good - I have a 575 W pulse start Venture lamp, and a 600W HPS lamp - also very good - paul m.

if you have a light meter, you can find it out for yourself, exactly how much illumination you are getting at what distance. I find that metal halide or hps (HID) will grow plants taller than fluorescent. Fluorescent is good for up to 8-12", taller than that and HID is better, at least with me.

HPS/HID is the way to go.

Most grow light kits will have a lumen raiting that you can use to compare against the same watt rating of T5 or any other kind of lighting.