I'm one of the few who isn't as impressed as everyone else is with the vortech pumps. I've got 2 on my 30long, and they are definitely nice, but IMO, not worth the hefty price tag.
I think it really comes down to how much "stuff" you want to see in the tank. If you really want to keep it clean, than a vortech is far and away your best bet. If you don't mind seeing a little, I'd probably block off the stock return and run the return over the top of the tank. I'd run 1 big return line split 3-4 times, then use locline fittings to really control the flow. That will give you the most flexibility and probably cost you less than a vortech.
If you want to be able to keep anything, then make sure you go with something you can control the flow rate on. The vortech controllers do it if you go that route, so that's not a problem. If you go with a bigger return pump, make sure you run a good valve so you can dial back the flow if/when needed.
With all that said, I'd be looking at the most flow you can afford. I think 500gph at the output is an absolute minimum, and wouldn't hesitate to look at something around 1000gph.