Granada to Barcelona...train or plane?

I would fly since in only takes 1 hour 30 minutes versus well over 6 hours if you took the train which requires you to go in an opposite direction to Madrid to get to Granada. I've never heard complains about the airport. People in the same situation as you apparently use it to go there to see the Alhambra as there are 4 direct flights a day from Barcelona peak season

The flight may only be 1 hour 30, but there is travel at each end of the flight between the city centre and the airport - allow an hour at each end plus you need to be at the airport plus you will need to be there say an hour before the flight if Covid checks are being undertaken (longer if you are checking a bag) plus say 30 minutes to land and deplane. Five hours is still quicker than taking the train.

During the winter, there is only 1 direct Vueling flight a day, 4 some days in the summer. If you are travelling on a day with only 1 flight and this gets cancelled, taking the train would be the quicker option.

Why would Granada airport not be decent?

Granada’s airport is about 20 minutes from the city center. We flew out of it to Paris in November 2019. It’s a small airport with one terminal and just a few gates. There is one boarding area. I think we arrived 2 hours in advance, and it took us no more than 10 minutes to check a bag and go through security. I much prefer those little airports to big ones.

Taking the train is without a doubt the most practical option. From central Granada you travel to railway station, board your train, sit down and six hours later you are in Barcelona, no faffing around with security checks, waiting at the gate, being unable to use electronic devices when you want etc.

There is a direct train from Granada to Barcelona in 6:10. Flying will be a bit faster, but travelling by train will give you six hours you can use as you like, have lunch, read, watch a movie, plan your stay in Barcelona and so on. Flying will take around five hours city centre to city centre and you might have 1-2 hours at most of useful time.

It also depends on cost. If you manage to find a cheap flight (allowing for luggage surcharges as needed), even if you factor in a cab to the airport in Granada and the suburban train or aerobús in Barcelona, it might end up cheaper than the train.
And yes, it will definitely be about 2 hours faster, all-in. And possibly even more, because I am not finding any direct Granada-Barcelona trains right now at random dates in Dec and Jan.
Now, I would personally still opt for the train for environmental reasons, but I still acknowledge that it is probably not the most practical option here.

If you can take a direct overnight train and sleep in a sleeper car, do it otherwise why waste an entire day on a train. I am an avid train traveler but prefer flying if it’s going to take six hours to get to my next destination.

Well, I hate everything about flying so if it's only about an hour more (total time, door to door) I choose the train, with all the benefits already mentioned. Would you have to check bags if you fly? Check what the cabin baggage limits are. That will add a little time to the trip.

I looked at the train and plane schedules. In spite of my preference for trains, it does look like flying is a better option in this case, if price isn't a deciding factor.

Thank you everyone for the replies and advice. Our trip is a bit away yet so I can't yet check prices.

How is Vueling in general?

How is Vueling in general?

They are the leader in domestic air travel in Spain. No frills but they get the job done, I've used them many times with no major complaints.

We made this same decision last summer. One of us hates to fly, so we usually take the train whenever possible. When we looked at the length of time for the trip and the price, we decided to fly. It was about the same price, but save a great deal of time, which is often more valuable than money when we're traveling. The flight was easy peasy and quite unmemorable (which is always a good thing). I recommend flying.

And possibly even more, because I am not finding any direct
Granada-Barcelona trains right now at random dates in Dec and Jan.

I found a daily direct train when checking a few random dates in December.