Athens to Naxos: Ferry or Airplane?

Hi - we're traveling from the US to Athens, staying a few days, then going to Naxos for 4 days and back to Athens. Then fly out the following day. I'm hesitant about the ferry because I don't want to lose half a day traveling by ferry. My partner can get motion sickness, and worried the fast ferry might not be a great option since there is no seating outside and looks like you need to largely stay seated during travel.

Leaning towards a flight between Athens and Naxos instead, but not sure about how long it would take to clear security at the airport.

Ferry is about 4 hours, 5 if we take the slow one where we can sit outside and generally walk around. Flight is only 40 minutes. For those that have taken the 5 hour ferry, was it nice and relaxing sitting outside looking at the view or did it just feel like a long boat ride?

Traveling in early May.

Thank you for your advice. I've been crawling through this sub to get hotel and trip recommendations. You guys are great providing people with all this advice.