Our new ride came with the previous generation Garmin 7612xsv, including radar and depth, an older Raymarine AP not connected to the plotter, an older ICOM VHF not connected to a GPS... and some other broken stuff.
The Garmin system needed both software and chart updates. Garmin support on that was good, and the updates were easy. (Only had that one contact so far, so not an in-depth comparison, but I'd say that once was equal to Furuno response on the few times we've needed help or info from them.)
I don't have a huge amount of time on the Garmin system yet. I've discovered (proved) I can't reliably touch a specific icon on the chart, even including the + or - sizing icon. Even in dead calm water, or even at the dock. We have no hard buttons as alternatives, so sometimes recovering from a mis-touch (?) takes a bit of time/work.
The charts are OK. Deciding how much data to display comes with some odd choices; "normal" doesn't display some I'd like to see, the next level up shows way more than I usually want to deal with. I miss having raster charts (as we did with our previous Furuno NN3D system) but then I guess USCG is phasing those out so I would have to bite that bullet eventually anyway.
Apparently Garmin chart updates occur "occasionally". Ours had G2 charts, and I updated to the current G3, at no cost. No clue how long these charts will still be considered current. Seems like these charts cover "everywhere" (at least for us). I was more comfortable I think with the "at least annual" NOAA chart updates we downloaded, free, with the Furuno system. I've read Explorer Charts are semi-mandatory in the Bahamas, but I didn't see a way to get those on the Garmin (but then I didn't spend a lot of time researching that, either), whereas they would have been available on the Furuno system via the optional C-Map charts I could have added.
I generally prefer having radar displayed on a separate screen, but gaining the ability to overlay radar on the nav chart is a nifty option and we actually used that to good effect a couple of times in heavy thunderstorms. Color radar is also nifty. I haven't focused on learning the tuning options on the Garmin yet.
We noticed some existing nav aids were missing from the chart... or maybe it was a function of whatever scale we were in at the time.
The 7612xsv looks like it's 5 years old, and reading suggests Garmin support will tail off fairly quickly... if so, that'd be unlike what we experienced with Furuno and their support for a couple of the (now) 18-year-old components we inherited on the previous boat.
After I think about it for a while, I'll sort out our complete system-to-be. Another depth finder (or maybe fishfinder), another MFD, AIS... plus another VHF and a loud hailer... with everything actually connected as necessary...
Excepting radios, that build-out could end up being all Furuno (bag the Garmin stuff), or mix-and-match Furuno and Garmin, or more likely all Garmin simply because of the cost of replacing a functioning radar.
But I won't be jumping into that immediately, giving myself more time to use this boat and think about it all, first...
-Chris