Barcelona - Porto, Portugal on Vueling Airlines.

Vueling is totally fine, just be aware that their base fare does NOT include any sort of luggage beyond a small underseat personal item. Cabin luggage is extra, and cheaper in advance/bought together with your ticket.

I can’t comment on either RyanAir or Vueling. Just curious if TAP is still providing flights from Porto to Spain? Several years ago (pre Covid) we flew TAP non-stop from Porto to Madrid. It was economical & great experience. 5 days later we took the train to Barcelona. As a European carrier we were very pleased with TAP’s service at the time.

We flew RyanAir, no problems, on time. Our other choices were not non-stop.
We paid a fee to board early and to reserve specific seats.
Vueling canceled a flight close to departure causing us to have to redo a good part of our itinerary. These things happen but I don’t get your Vueling over RyanAir. Choose schedule and price.

I would put Vueling on a par with Ryanair. Go for whichever suits your schedule.

We flew Vueling from Granada with a connecting flight in Barcelona to Paris. It did the job of getting us from Point A to Point C. We had to board at least one of those flights (can't remember if both since this was three years ago) outside. We stood on the stairs for at least 20 minutes waiting for those in front of us to board. It was windy and chilly in early April. Vueling did lose our luggage which cost us the first 1/2 day in Paris while waiting for our bags, but this happens with many airlines. All were minor blips and I would fly Vueling again. It got the job done.

I used Vueling from Barcelona to Vienna. I would use them again. I wouldn't have known they are a "budget" airline had I not been told. Plane was clean, staff was pleasant at check in and during the flight. The only "sort of" negative was there were no snacks served nor do I think they provided beverage even water.