We use a tax professional. I did our taxes myself while we were working; it was usually the EZ1040 form. But once we took retirement, I was tired of both managing the asset portfolio and doing the taxes, so we now use an independent CFP firm and are on our second tax pro.
Our first tax adviser was a family friend - very good but he was elderly. After a bout with skin cancer, he became noticeably frailer. I finally decided to find someone closer to us and was referred to the woman we now use. She mostly does work for small businesses so she considers us one of her "easy" clients. This is our second year with her.
As we take regular distributions from our taxable portfolio, it's worthwhile for us having pros for both asset management and tax filing. Our distributions are managed with an eye towards taxes, which definitely helps keep our effective tax rates lower.
This is important as Spouse's pension is fully taxable which thus bumps my SocSec into the highest taxable bracket.
Our federal and state tax forms totaled 42 pages this year. We figure our CPA is worth every penny of her cost.