With only 10 days and wanting to also do Crete, you may not be able to do what we did, but it worked great. We went from Paros to Crete, and that required a ferry change in Santorini.
So we reserved one of the best hotel views for one night and went in to Santorini for one afternoon and back out to Crete the next day. It gave us time to see both major towns on Santorini, eat dinner on the water for sunset, and have an incredible view from our hotel room. We avoided most of the crowds this way. Worked great.
We stayed in Heraklion on Crete for the sole reason that we could get both to the west side and east side of the island easily. That ended up working fine. If you have no interest in activities on the east side, I would stay in chania or somewhere on the west side, particularly if the beaches and/or major hikes are important.
Greece was awesome. One of our favorites trips.
edit. Accidently typed crete instead of Santorini when describing the two towns.