I really like the browser integration, which there isn't anything comparable for pass. I had a bash script [0] which when run would pull the current URL from my browser, and run pass to generate or copy the password to the clipboard - but the 1Password extension is so much nicer. If I'm on a site with weird requirements I'd have to figure out the params to make pass generate a password which matched it; with the extension I just click a few buttons.
I've also got hooked on the iOS app. I didn't know there was one for pass, but it looks rather basic compared to 1Password [1]. 1Password also supports TOTP, so you don't need a seperate app for that - although for security you probably should.
Maybe one day I'll get around to writing my own extension and app for pass, but for now paying $60/year is worth it for me. I don't pay for many apps/services, but this I find really worth it.