I've used multiple email provider web mails (Gmail, ProtonMail, and my current provider fastmail). I have also used various clients over the years, haven't used thunderbird in a while but I still use mu4e in emacs as well as neomutt (terminal email client). In terms of feeling "smooth" the web clients have always been superior to the thunderbird, but it's been a couple years so maybe thunderbird has improved. Mu4e and neomutt are equal if not better than most web mail clients but since I always have a browser open I usually just have a web mail tab pinned. I wish I could use thunderbird, I've always liked its design, but it has a hard to describe quality which makes usage "clunky" feeling.