Certainly Bharain is one of the more preferrable locations in the Gulf States and has a lot of social plusses for the Expat (Booze available in hotels and restaurants, tolerant multicultural environment...in many respects similar to Dubai). However in my opinion, and this depends on how long you anticipate bring there, it can become a tad claustrophobic. It is connected to Saudi Arabia (Dammam) via a causeway, but you can only gain access with a sponsored business visa (why anyone would want to go their for any other reason defies the imagination!). Dubai gives you good access to get out into the other Emirates, visit Wadis, go Dune Bashing, Horse Racing, play Golf etc etc.
You coud even drive through the desert highway into Oman some beautiful scenery there. So my personal top 3 of the Gulf states for expats would be 1. Dubai (UAE) 2. Oman 3. Bahrain.