Hi all, came across this very interesting recent video from English youtube channel called Spain Revealed that reviews the 4 different high speed train operators on the most popular route in Spain, from Barcelona to Madrid. I know that the ever-evolving high speed train ecosystem in Spain is a bit confusing to foreigners (seems like every week there are questions about it here lol!). Hopefully this video can demystify it for you all. He looks at:
AVE (Spain's original high speed train)
Avlo (Spain's new low-cost option)
Ouigo (French low-cost option)
Iryo (Italian mid-tier option)
TLDR is that all operators were good options, but that Iryo was his favourite because it combined the low cost of Avlo/Ouigo with the higher standards/comfort of the AVE, only downside was that it did not have too many departures compared to the AVE, but was often half the price of the AVE.
As for booking, he recommends the website Trainline (though he does get a kickback from that site).
Here is the link to the video - https://youtu.be/AWh1XikSMOM
or just search on YT - "I rode EVERY Spanish fast train (and this one is the best)"
Hope this helps :)