Best Filter With Sand Substrate

[Kaida]

I'm intending at some point to build myself a tank around 4' long, 1' deep and 1'-1.5' high. I want a pair of L183 plecos, and a betta of some form. I know plecos are messy, so over-filtration is a good idea, but I don't want too much water flow since bettas aren't overly keen on it, so my initial thought was that undergravel would be best. But I would like a sand substrate, and I think the plecos would too. So which filter would be best? Also, is there a way to get a current along say a third of the way up the tank, while leaving the top area still-ish?