We sent some newly certified students to dive with Dive with Natalie and Ivan, on the recommendations of a friend who lives and teaches down there. They were extremely happy with their trip, and have used the same operator on subsequent visits.
Akumal itself doesn't have much in the way of resorts. If you are looking for something fancy and all-inclusive, you will need to look in a more general area. The Akumal Beach resort is pleasant but very basic.
Last summer, my teenage daughter did her first ocean dive with Natalie as DM, and she was top notch--best DM I have seen. She did a thorough predive briefing, was attentive during the dive, and did great post-dive debrief with the new divers in the group.