Actually they both have casinos. The Maho one is located within a bustling town atmosphere and the other is close to Philipsburg but not recommended for walking to at night. I have never stayed at either but stayed in a timeshare next to the one in Maho. The Great Bay one is more isolated and the Maho one is a good central point to get anywhere. If you like traveling to Orient every day, I would choose Great Bay. If you enjoy the Dutch side and occasionally go to Orient, then I would choose Maho.
Also, if you want peace at night, choose Great Bay and if you want the hustle and bustle of nightlife in a walkable distance, then choose Maho. It's a toss-up on the rooms in Maho. Some people get stuck with rooms facing the street and find the noise disturbing. Sometimes you can ask for a room change but if the hotel is filled, then there may be a problem.
Mostly, the reviews I've heard from Maho are very good...great pool with swim up bar...staff is accommodating...great restaurants within walking distance....beautiful views if you get the right room. Once in a blue moon someone comments that they did not enjoy it due to the sewer smells. In 13 years of staying in Maho, I have never smelled any sewers but then again, I could be wrong.
The reviews I've heard from Great Bay are that it's a nice place to stay and convenient for getting around the Philipsburg/Orient area. Not much else.
Life is not a child's game of follow the Leader. Instead, life is more about finding one's own purpose in life....your life's plan, and then making a positive difference on earth.