Depends on how many plants you want, and the light requirements of the plants.
For 125g, Four 4' florescent tubes is plenty. They're usually 32 watts per bulb, so thats ~128watts of light, or 1 watt per gallon.
60+ watts worth of LEDs would work too. LED flood lights or LED ribbons like this work too:

I've used both. Florescent lights are cheap and easy. I prefer LEDs because it makes the tank "shimmer" a little bit more, is quiet, reliable, no flicker on turn off/on, no bulbs to replace, less heat, generally less power hungry etc.
If you go with LED flood lights or LED ribbons, just make sure to get enough wattage. I think 60 watts is plenty for some basic plants. 12v light ribbons with a 12 watt power supply is a pretty easy way to do things, you can just staple the led ribbons to the top of your hood with a staple gun.

For 125g, Four 4' florescent tubes is plenty. They're usually 32 watts per bulb, so thats ~128watts of light, or 1 watt per gallon.
60+ watts worth of LEDs would work too. LED flood lights or LED ribbons like this work too:

I've used both. Florescent lights are cheap and easy. I prefer LEDs because it makes the tank "shimmer" a little bit more, is quiet, reliable, no flicker on turn off/on, no bulbs to replace, less heat, generally less power hungry etc.
If you go with LED flood lights or LED ribbons, just make sure to get enough wattage. I think 60 watts is plenty for some basic plants. 12v light ribbons with a 12 watt power supply is a pretty easy way to do things, you can just staple the led ribbons to the top of your hood with a staple gun.
