The experience with KDP Select seems different for each author. As others have said, try it out and then decide after 90 days.
In my case, I started with Select, opted out for 6 months, and am now back in Select. During those 6 months, I sold less on all other platforms combined than the amount of "borrows" I get in Select for a single month. Plus, I get 70% royalty in India as part of Select. Those two features are enough to keep me renewing.
In my case, I started with Select, opted out for 6 months, and am now back in Select. During those 6 months, I sold less on all other platforms combined than the amount of "borrows" I get in Select for a single month. Plus, I get 70% royalty in India as part of Select. Those two features are enough to keep me renewing.