@Globalcitizen
Lanta vs. Lipe
1. Koh Lanta is huge when compared with the tiny island of Koh Lipe. Your own leg power will determine where you would like to go but you will need a motor on Lanta.
2. There are many beaches on Lanta offering various accommodation to suit your budget.
3. Diving from Lanta is expensive by Thai standard as the sites are far but not sure how the operator carries out the rescue course.
4. Koh Lipe is another 3hrs by speed boat from Lanta and the cost of living is slightly higher than Lanta but not significantly. A lot of nonsense on line.
There are many established operators on both islands and I had dived with five and they were all competent.
If you have time than you ought to visit both islands.
Another option is Khao Lak which is about 2hrs from down town Phuket.
Enjoy the Kingdom.