well for a first time visit for your friend...I'd pick Xtabi.
We did visit and tour Banana Shout....looked to be an awesome spot..great location right beside Ricks and all but the gals we spoke to that stayed said that the water was a bit of an issue. Not that they minded...not that it ruined anything for them but for first timers I'd want to make sure the basics were all there.
We haven't stayed at Xtabi yet...we are on our way the end of the month. We ate many meals at Xtabi 5 months ago...and that's partly why we looked into staying.
We stayed at Samsara on our last trip, in one of the Pillar houses. That was a neat experience, with transfers to the beach that are included. Nothing wrong with Samsara but we always like to check new places out. Thats my 2 cents for what it's worth.