What are the advantages of applying for a Thai O-A retirement visa from your home country compared to applying for an O visa in Thailand?

If you get the OA, you don't need to check in with immigration for the year? Is that what yall are saying?

As you get older, and stay longer, the O option advantages outweigh the OA advantages in my view ....

Sorry I mis-remembered what you asked

you're asking about doing an OA in your country (where you show proof of funds there, show the mandatory 3 million baht insurance, do the police background check and medical certificate

versus

getting the O visa/year extension inside the country which you show proof of funds inside the country but doesn't require a police background check, medical certificate OR any insurance

The OA visa can afford a person almost 2 years of stay (so no need to bank any money here for that time) as long as you exit/re-enter the country just before the VISA itself runs out (and you have another year of the mandatory 3 million baht insurance). You'll get stamped in for a whole new year (or as long as your insurance is good for)

Many people were taking the OA visa when it had the lower insurance requirements 40k/400k out/in-patient coverage but since it went to the 100K USD, (3 million thai baht) coverage a LOT of people are getting off them and getting an O visa then the year extension

Sorry I didn't read your initial post correctly, I deleted my bad response

Another small point might be: with Non-OA you can stay up to almost 2 years in Thailand without needing to go to the immigration office, with one application (and one border-run). Works for some people living far from Immigration offices but still traveling at least once a year.