On a 120, I'm a fan of the VorTechs. You can "do a lot" with them with surges and other flow variations. They are magnet-driven and the power is all outside of the tank (no heat or electric lines in the water). On the down side, you can't aim them in any and all directions. However, a couple of VorTechs put out a lot of flow, so you really wouldn't NEED to pinpoint aim them. My preference is to set one on each end, or if you scape it in a way with both on the back wall toward either end, some neat things can happen (especially with a bowfront or half-circle tank, but that's irrelevant).
They are pricey. No doubt. Their customer service is the absolute best I've seen in the industry. They have never failed to demonstrate great service when I call in.
Outside of VorTechs, call me old school, but I like the Koralias a lot. They've always performed well for me, and the price is much lower. I like their "bang for the buck."
Hope this helps!