GoDaddy has reasonable selection, prices and often promo codes to reduce the cost. I’ve purchased through them without difficulty in the past. Nothing lately.
I’ve purchased from Comodo to install specifically on various InMotion Hosting VPS. Much better experiences the last half dozen times versus several years ago.
Been looking into the free LetsEncrypt, yet I haven’t been able to make it work for me. It’s not easy to set up. Actually may be easier to just find a web host that offers it included.
Ultimately you should check directly with your hosting provider what they suggest AND if there’s anything they wont accept for your specific type of hosting (Shared, VPS, etc.). Talk to their customer support and read their online help/support files.
You might also look into Cloudflare.
Hope that helps.