Airlines - which ones are the best to fly

The best one is the one with the best prilce that fits your itinerry.

I would mostly agree with Norma, but there are other factors as well: seating comfort, on time performance, food service, baggage allowance and cost of add-ons.

Only you can decide how important each of these factors is for you.

And I would be willing to bet that you can find people who have had excellent and abysmal experiences on all of these airlines.

Try https://www.seatguru.com/ for seating comparisons and https://www.flightstats.com/company/monthly-performance-reports/airlines/ for on-time performance.

But you probably have to go to each airline web site and do some math to get a pricing comparison.

So Norma's advice might be the best: find a flight that fits your itinerary and your budget, and don't worry about what you should have done.

Since they codeshare with each other, any flight bought on one of their sites could actually be one of the other's planes and depending on where you are flying from, may not even exist on that named airline (for example, from Philadelphia to London you could buy any of these, but the only actual flights would be AA or BA).

All of those airlines are in the oneworld alliance. They code share flights as Larry mentioned so you need to look at the flight to see who is actually operating it. I have not flown Finnair but have flown Iberia, BA and AA. Economy on each of them is fairly similar. As Lane mentioned, Check seatguru.com for specific seat details. If you upgrade to business class, check the plane type for a specific flight and check seatguru for details. I believe Iberia has updated all of their business class seats and they are really good. For AA, it depends on the plane. The A330 is really nice but the 767 depends on whether it is the updated version. BA has the same business class on almost all of its planes and they have the worst layout as far as I’m concerned. The seats are narrow and alternate between forward and rear facing seats meaning someone has to climb over someone else to get out of the window seat.

In economy I don't think it makes much difference. They are all pretty much the same and miserable.

I go with the best price in premium economy mostly .

My view is pay the least and fly the shortest time. I live in San Diego and usually it is cheaper and quicker to fly out of LAX. That being said "read the fine print" when booking! Last trip to Europe airberlin went bankrupt but the German Govt guaranteed tickets. This trip to Amsterdam we are flying Icelandair, one of our flight segments was cancelled by the airline. I booked through Justfly, they fixed the problem for free. Our trips over were on 787's, very nice plane but 10-14 hours in a steel tube is easier to deal with on the way over because the anticipation of getting there. We also have a flight to Rome to join the RS heart of Italy tour, on Air France, which is on strike!! Don't know what will happen but we have until September to figure it out! Stuff happens!!
Just get there and use the money saved on business class for several splurges when you get there!! Enjoy

If you specify which airport or airports you are flying from, and which ones you are looking to fly to, people can give more specific advice.

And yes, since these four airlines are all OneWorld, you may not have four choices of flight - just one or two flights under different flight numbers. Just so you know the lingo, this is called "code sharing," and the actual operator is called "metal." So, if your flight is nonstop from JFK to Helsinki, it's "Finnair metal" but may have a BA, AA or Iberia number as part of their code-sharing agreement.

It's important to know who's actually operating your plane, so you go to the correct place for check in. For instance, at JFK, terminal 7 is used by Iberia, BA, and Finnair, while AA uses terminal 8. In large airports, you can waste a lot of time going to the wrong place!

Other things being equal, I think that AA still doesn't charge to select a seat at time of purchase for a standard economy seat and BA (and possibly Iberia do)

The best airline is the direct one.

I just flew to London on AA and returned on BA. It's been a while since I used AA and this was my first time on BA. They were basically the same in economy. AA was on a 787 Dreamliner, but had 3 X 3 X 3 seating. I was lucky enough to get an aisle and no one next to me. AA had an excellent selection of on demand movies, including almost all Star Wars movies as well as Marvel movies. I"m the type that prefers lighter entertainment on the flight. Since I often travel in May, the on demand movies have often been mainly heavy and serious Oscar bait type films rather than popcorn movies. AA wasn't at all stingy with the drinks, which was nice. The food was edible. But, I chose this flight specifically because it was a unique day flight, leaving Chicago at 9 AM to arrive into London Heathow around 10 PM. I've had awful jet lag during my last two European trips so I was determined to beat it this time.

My return flight was on a gigantic BA Airbus 380-800 double deck plane. It was just about completely full on the upper deck. Decent enough on demand movie selection, food was pretty good, but the drink service was stingy. 2 drinks served, and then the flight attendants hid behind a curtain as if they were The Wizard of Oz!

To sum it up, I don't think it makes much difference. I used to enjoy Virgin Atlantic, but they pulled out of Chicago. I would say they're a bit better in economy.