You'll have to decide if you want the beach, for a little more, or the cliffs.
I wouldn't worry about walking from any of the places. Even if back from the main road, like Oasis, you just walk to the main road and catch a route taxi - very cheap.

My last trip, in March, I tried NBCC for the first time - it was great. As irieworld warned, make sure you are dealing direct with NBCC and not Mariner's - best way is to contact Jean Gaynair directly.
Her ph#s in JA are 876-957-4323/4754. But they also have a US ph# 954-840-7119 connected to them in JA using Magic Jack. Email is gaynair@cwjamaica.com
She is great and will work with you on price - I told them what I could afford, reasonable amount based on others in the area - and she was able to get me a great place at under advertised price - but I think that always works best in person and at last minute when they know the condo would go empty. At Thanksgiving probably have to pay advertised rate and reserve in advance.

I toured Oasis, the trip prior, and have to admit I was impressed. Great looking grounds, pool, and pool bar - and only place I've seen with tennis courts.
But if you are considering Oasis, did you look at Seastar - also back a little from the road, but better priced than Oasis and always gets rave reviews for their guest treatment - is my all-time fav.
NBCC has kitchens in all condos, and Seastar has in some rooms. There is a little market right at the end of Seastar Lane.

Another budget choice on cliffs is Catcha Falling Star Gardens. Not the main Catcha property, but they have added a new pool at Gardens. I have not been, but seen ads on this board for great prices and see good reviews.

Just my 2cents.