I guess the level of instruction would be the deciding factor for me. Just because the one is an official certification class doesn't necessarily mean the instruction will be better. It might in fact be worse.
If these guys do in fact know their stuff and if they take the time to instruct you and explain the hazards, then I'd go for it. If on the other hand they just expect you to put on a bunch of loaner gear and jump in the water, I'd stay away, now and in the future.
Day after day we hear from students being misguided by certified instructors. How can we expect an OW candidate who hasn't even been to class 1 to recognize the competency of these friends.
SOP instruction has academics, confined water work then finally open water diving. How people respond to diving has a lot of variables. Instructors are trained to spot and mitigate those problems. Jumping to the end game may have unanticipated consequences.
Get certified first, the reef will wait.
Pete