I've stayed at both Yensabai and Mosaik and both are fine. Yensabai has a large and well-kept pool, if that matters to you; Mosaik has none. Both are condo-type accommodations so no breakfast available, but there are many nearby options. I think Mosaik is slightly more expensive and, in my opinion, has slightly nicer rooms on average; the Yensabai condos have various owners so quality varies, but none I saw were really run-down. Both are fine with (legal-age) joiners--no fee; Yensabai checks and (I think) holds IDs. Everybody mentions Mosaik's hard beds, but I didn't find them so. Yensabai actually overlooks Sunee Plaza on one side; Mosaik is a few short blocks away. The office at Mosaik is friendly and easy to deal with. The Yensabai manager(?) is horrible, but the desk clerks are fine, and if you rent through Pattaya Rent a Room(The Austrian Consulate) across the street, they're fine too and you shouldn't have to deal with the Dragon Lady. I'd happily stay in either one again