I have a strong preference for Yealink. I've been doing 3CX for approaching 20 years and this is the brand that has always been supported, and in my experience rock-solid.
I have had far less favorable experiences with Fanvil, but it has been a few years since I tried a Fanvil. I suggest you Google the 3CX supported phones list and stick to the list. Support for Cisco, Polycom, and others have come and gone over the years, but Yealink is always on the list.
Be careful with WIFI phone connections. Use them sparingly, and ensure your WIFI infrastructure is highly reliable. Make sure you can configure whatever phone you choose to turn off the display (go to sleep). People get really grumpy when the hotel room has bright phone displays keeping them awake.
POE is a REALLY good idea, but it depends on quality wiring, something not always available in an older hotel. As a guest, I'm always looking for an available wall outlet, and consuming a strategically placed wall outlet with a phone power brick is frustrating for the guest, and it's one of those things people can take and the maid may not notice right away (since the display will be off most of the time).
