I'm assuming you already have a pole, and vac hose?

The Rainbow ProVac is what I've used for years. We have a big one at the country club pool we service. They are very fast and effective, with adequate suction, but are expensive and some folk take a little while to learn to 'steer' them:
Pentair ProVac page
Rainbow R201276 ProVac Commercial Vacuum Head 14" @ Amazon
However, many people prefer a combo brush & vacuum like this:
Pentair Vinyl Vac page
RB triangle vac @ Amazon