I haven’t used either, but if I was to stand up one over the other, I would go with 3CX. It looks more mature and it doesn’t require 3rd party software for smart phones or desktops. They offer a free version (25 users or less) that I’m sure can handle call forwarding.
Currently I use O365 E5 for my business and it just works. I have the app on my phone and desktop to answer calls. It’s all in one supported package which is good when trying to run a business.