I have several DStar radios and have focused on that. A couple big reasons...locally, there is considerable infrastructure supporting DStar (and all of it links, which is probably what everyone wants to do with digital repeaters). Two, the low speed serial function can be fully used (unlike Fusion) and can fully function as a sort of more sophisticated packet channel along with voice. We use it for Emcomm with D-Rats software. It even does internet email like WinLink.
As far as voice, I had a Fusion radio and I didn't think the audio was any better. The re-sync WAS better on Fusion, no question. The other stuff like GPS was the same. D-Star pumps DPRS into the APRS-IS system (as about all repeaters are connected to that). You cannot message each other, but you can do position (which, honestly, is 99 percent of APRS om actual use). Yeah, DStar is long in the tooth as far as digital modes go. Still works, though. And we have a real Icom repeater here connected to a cross-mode gateway so we talk to DMR (mainly), Fusion, P25 and NXDN all on the same repeater. Requires a couple higher-end AMBE chips but it really works well. The other modes come in via a hotspot or a linked repeater native to that mode.