Dude let me tell you, you dont want to do your open water in october. I did mine last year in october (1st week I think?) and it is f-ing cold.
As for a recommendation I found that PADI is more universally accepted and more PADI dive shops around. I could be wrong but it seems that way..... Its not as advanced from what I have read/seen but it will do the trick. We went to an island in Venezuela population like 50 and it had 2, PADI and I cant remember the other. Some places dont accept PADI vs. others and vice versa if that makes sense.