Everything else after opera dropped Presto and became a chrome clone felt like a downgrade to me. I never got the same feeling of easy of use and control over a browser. I kept using the 12.16 for as much as I could, then switched to firefox. The new "opera browser" now is a different browser just sharing the same name.
And the beloved opera mini for the mobile was amazing. Back then I would even use it in a vm on my computer sometimes because I had shitty internet (and to use a proxy).
When Opera became just another Chromium skin I switch to Firefox. The point for me was Presto, that Opera was really well put together in terms of UI was just a bonus. The developer tools in Opera was better than what shipped in Chrome and Firefox, so switching definitely felt like a downgrade.
Someone, I don't know who, but I assume the new Opera, is still keeping the Opera Mini proxy servers running. It show up in our logs frequently enough that we noticed and have special whitelisting for them to byparse some rate limiting.
Vivaldi feels like Opera did (makes sense, since it's the same CTO).