1st time, should i cancel Naxos and go to Santorini instead?

Really a personal thing—some cannot imagine going without seeing [insert whatever famous thing here]—and the crowds show it! But only you can gauge your interest in seeing it. I personally would not prioritize that way. I’ve always found doing something even only marginally less famous to be exponentially more enjoyable.

You won’t miss anything by not going to Santorini but crowds and more of your money

I’d choose Naxos over Santorini any day - and have for last few dozen years lol

I assume you chose these islands because you did your own research and they matched the experience you were looking for. So why change your mind?

Santorini is a mass tourism destination, which is why it's recommended by so many people. Most have never visited other Greek islands.

However, I'll repeat my advice from another of your posts, which seems to have been overlooked: visiting three islands in a 13-day period will mean spending a lot of time traveling by ferry instead of enjoying the islands themselves. With only three nights on an island, you're left with just two full days. Far too little for places like Naxos and Tinos.

We just did both and you don’t say when you are going, but here is my 2 cents. While we did like Naxos, quite a lot actually, we found there were more things we enjoyed doing on Santorini. The history (Akritori), the beautiful caldera view, the spectacular hike from Fira to Oia and the 21 wineries. We are not beach people. My top recommendation is to go in shoulder season and not during the summer months.

We did not like Santorini in February. Everything was closed and even with just our ship in port the streets were crowded. In high season there are often 5+ ships in port. We did have good weather, though, which was a surprise.

NO! Santorini is meh. Naxos is fabulous!

Cruise ships go to Santorini and it can be crowded. Plus, there are no good beaches. Cruise ships DON'T go to Naxos and the beaches are amazing.