You have a ton of great options here for sure! What I would do, which would give you plenty of light, even ran at low settings is shop the marketplace here. You can find a Radion Xr30 g5 for 500 dollars or so. Thats a great deal for the light and that bad boy can put out so PAR and you would only need one for a 20g for sure. Plenty of power to grow any sps for sure.