Reethi Rah, without a doubt. Gili Lankanfushi was great few years ago, especially Crusoe villas. But it's getting a bit long in the tooth now and it's VERY rustic version of luxury, check first if that's your thing.
Conrad's saving grace are jacuzzis on balconies, but the place is full of point spenders and Chinese tourists.
Regards,
El Puerco Volante