I've been to Bali once (Ubud, Kintamani and Nusa Dua) and to Maldives eight times. Personally, I prefer the Maldives (Meedhupparu, Kanifinolhu, Farukolufushi, Meerufenfushi, and Summer Island). While we found the Balininese to be warm and friendly, we found the island to be in horrible condition. We saw a tourist get seriously hurt falling through a giant pothole on the street. Both Kuta beach and the beach in Nusa Dua were in deplorable conditions with lots of garbage floating around. The rain washes all the garbage from the village into the river which then spills into the ocean. At low tide it felt like you were walking into a garbage landfil. Venturing into Denpasar, you must be vigilant not only for the constant approach by people trying to sell you souvenirs but also against theft.
Your experience in Maldives will have less to do with how much you pay per night and more to do with whether or not you get a genuinely friendly resort.
Add to that perfect weather (December-March), miles of crystal clear water with no waves, amazing snorkeling and diving, and an impeccable safety record and you got pretty much heaven on earth.
We're going back again in February.