In Krabi province (Krabi town does not have a beach) there is far less traffic so, with transport, the beaches are far more accessible. Klong Muang, Tubkaek and Pan beach are unpopulated beautiful beaches.
Long beach (Hat Yao) is 10km of empty beach. Railay is beautiful but busy in the season.
No Jet skis, no hawkers, no banana boats make the beaches IMO much better.
Prices are better than Phuket
Virtual absence of naughty night-life is a bonus for some.
Each to their own, but the absence of traffic and the laid-back atmosphere make this a better place for me.