Recently I bought an unlocked phone for my Verizon account and had some issues with texts but a quick trip to the Verizon store fixed that. I'm pretty sure I still have WiFi calling, not that I use it that much, but I have found that I can't call 911. I haven't gone in yet to talk to them about it but I can't see how they could deny me emergency calling.
One advantage is you will get updates sooner. So as Google releases patches, and OS updates for your device you'll get them without having to wait on Verizon, who usually drags it's feet and sometimes foregoes without notice. Less bloatware comes pre installed is another one. So none of Verizon's pushware. You can still get their apps in the play store if that's what you want it just doesn't come pre installed. There's also the advantage that you can get phones that Verizon doesn't carry, like my HTC U12 plus. I guess Verizon broke off from HTC to carry more Moto's and Sammie's. You can still have their insurance and so far their features. At least I haven't found any that I use that I haven't been able to get.