I stayed at Smart last year and had a quick look at Borneo Diver on Mabul but that was before they completed the construction. I think accomodation wise, they are similar except that Smart is a little more spread out, more trees. Smart does have a swimming pool and a slightly better public facility.
Service wise, I don't know about quality of dive guide at Borneo but Smart was excellent. Boat crews were very friendly. On Sipadan, if you are with Borneo Diver, you gear up in the gear shade then walk across the beach to the boat so you do all the work yourself, whereas with Smart, they will take care of all your gears and you just have to gear up and jump into the water. At the end of the day, they bring everything over to the rinse tank for you. A better arrangement for a lazy guy like me
Service wise, I don't know about quality of dive guide at Borneo but Smart was excellent. Boat crews were very friendly. On Sipadan, if you are with Borneo Diver, you gear up in the gear shade then walk across the beach to the boat so you do all the work yourself, whereas with Smart, they will take care of all your gears and you just have to gear up and jump into the water. At the end of the day, they bring everything over to the rinse tank for you. A better arrangement for a lazy guy like me