We have a Siemens Giga-set that is always in the top 2 of reviews. It’s not great in terms of losing connection to base station. When connected call quality is fine (it’s connected to a SIP exchange as we have no landline) and the handset itself is decent quality.
Hardly anyone ever calls on in tho, we mostly use WhatsApp or FaceTime. Our is probably about 4 years old but if it dies we wouldn’t bother replacing it. I have an ancient Polycom SIP handset I use occasionally for work stuff that runs off an Ethernet connection (again to a SIP exchange) that’s brilliant. But not very mobile 🙂