Hi Ruth,
I have stayed in Akumal 2x and enjoyed it both. I haven't been to Cancun, but wanted a smallish resort. The second place we stayed was a great experience. I can't comment on the condo/house option except to say it might not be as much of a vacation for whomever cooks in the family. I think some people like it to save money and have space. It depends on how you feel about giving up amenities.
I'll share with you the place that we stayed.
Club Oasis Akumal is now owned by an Italian company called VENTA resorts and they have a website. It is an all-inclusive that we found reasonably priced at the time we went (2 years ago) and time of year GREATLY affects rates. We didn't have one problem. The food was delicious, a mixture of Mexican-Italian-American. We happened to arrive on New Year's Eve and there was a great buffet with shellfish and lots of great stuff. The waitstaff was so nice. And because of the ownership there was an espresso machine at the bar and we could get lattes anytime of day along with pina coladas, etc. There was also nice kids club staff if parents want a break, and decent snorkling right off the beach. The first place I stayed years before had even better snorkling, but not as well run.
The downside of Club Oasis Akumal was that entertainment was just okay and there are some with better nightly shows.
Akumal is a 90 minute drive south of Cancun airport and I found a better deal with APPLE VACATIONS that included transportation. They may have had larger units on site; we had a hotel room and space can be a downside of the hotel option.
I love the Riviera Maya area, might try Tulum next time.
Good luck!
Cheryl