Flights to Santorini - is Volotea reliable?

They are all fine. Plenty of flights between Athens and Santorini.

Santorini is a small airport. I flew out of it earlier this week.

Volotea is a Spanish Lowcost Airline. Skyexpress is a Greek Airline, low cost too.
You will therefore have lowcost services with these 2 companies.

As I have already explained to you in one of your previous posts, with lowcost airlines be attentive to the additional costs for checked baggage and check the authorized weights.

Thank you for alerting me to review bag fees. I’m more concerned about connection times and as long as the price difference isn’t Insane, I’m looking for the best flight, really earliest, that would be reasonable to make after connecting.

Volotea is a good choice in terms of departure times. But sometimes the best choice is not the one you think.

I took Volotea flights several times (including 2 times in Greece) I had problems with delays twice. Once because a pilot had to wait (about 1 hour) for the end of his obligatory rest period before coming, another time (in Santorini) because they couldn't fit a passenger's wheelchair in the cargo compartment when everyone was already on the plane.
They asked the passenger to get off the plane because she did not want to travel without her wheelchair.
The delay was almost an hour.

The other times everything went well with Volotea

FYI In France, at Volotea there is currently a flight crew strike. It should end tomorrow.

According to the union's press release, Volotea's flight attendants are "among the lowest paid on the market", with the captains having agreed to cut their salaries by 25% and the co-pilots by 10% in order to help the airline get through the crisis. The measure ended at the start of the year, but in March Volotea management demanded a further pay cut.

I have lost count of the times I have flown with Aegean, I have never had any problems.
It is regularly ranked in the top 5 airlines in the world.

I've flown on Sky Express twice between Athens and a Greek island, without any problem.

I should add that I have flown Aegean three times in the last two weeks. No problems except that each time we were bused out to the plane. Arrived early on all three flights.

We flew Volotea from Bari, Puglia to Palermo, Sicily. No problems at all, less than an hour. We paid extra to choose our seat in advance and board early. It reminded us of Southwest.
We have also flown Aegean several times with no problems.
I would think you could make the Aegean flight.

Option 1 requires everything to work like the proverbial 'finely tuned Swiss watch'.

Not sure that is how I would describe airline operations, in the current environment.