Zoom Phone
Cheaper still, if the basics are enough
$10.50 per user on the metered plan, or $16 with unlimited calling on annual billing ($18 month-to-month). It covers what most offices actually use: auto-receptionist, routing, extensions, texting. For a team already meeting on Zoom, it is one fewer application to learn.
What you give up: Support is self-service first. You are trading away exactly the strength you were paying Nextiva for, which for a business without IT staff can be a bad trade.