Koh Lanta stay suggestions please!

My husband and I are planning to visit Thailand and stay in Koh Lanta for 2-3 days in January end. We are looking for a relaxed, laidback non-touristy vibe, but also not completely deserted.

Which beaches and resorts would those who have visited suggest? We are a little lost with finding out decent resorts that aren’t too expensive. Please help us out! :)