Well here's an alternate opinion. I always stay at the Hotel Santo. The Deco Stop is up the hill from town. That gives the Deco Stop "sunset picture points". Both hotels have nice pools, good in-house restaurants, and great staff and management who like the dive crowd. So they are equal from all those points. But the Santo is right in town for shopping, picking up small items daily, and going to other restaurants easily. Deco is away from town. But, remember "in-town" by Vanuatu standards doesn't mean the same thing it does in Oz or the States regarding traffic, noise, etc. We usually do a dinner or two up at the Deco, and then prefer to stay at the Santo for the convenience the rest of the time. So that should be enough info for you to decide what is important to you and make a choice.
But diving - use Allan Power, period, end of discussion!! No one has as much experience diving the wreck as he does and the two operations are not even comparable in my mind.