sjspeck was pretty complete, though I find it difficult to recommend Lahaina Divers or Maui Dive Shop.
Lahaina Divers' trip to Molokini is *long* -- you can plan on 2 hours or more each way, whereas the Kihei operators are there in 15 minutes or so.
Also, Lahaina Divers has standardized on 72 cu ft tanks. So, unless you request a larger one (and pay extra, probably), you'll be experiencing a shorter dive... and even if your air lasts longer, they're also less relaxed than Mike Severns, Ed Robinson's, etc. and may have you come up before you're out of air or NDL.
Maui Dive Shop is a large company and your experience can vary wildly based on which boat you end up booking on and the crew that day. Their rental gear is also in the sub-par category, but their prices match the amount of marketing they do.
That said -- if you're looking for shore dive rental gear in South Maui, Maui Dreams has the best and least-expensive gear you can find in active rental (unless you're on the Scuba Shack boat). In West Maui, it's a toss-up between Lahaina Divers (good new BC's & regs, old wetsuits, small tanks) and Pacific Dive (older BC's & regs, newer wetsuits and choice of tanks). Thankfully, those two are across the street from each other and you can get half of it at each location.