Earlier Raymarine products I had on a previous boat worked fine. Never needed service.
Furuno suite is excellent, and service has been very good too. OTOH, the only "service" I've needed was some minor advise about a known MaxSea
feature where Tides and Tidal Currents will cause a system slow down if left active for too long (the recent software
rev addresses that).
I have not owned Garmin, but a few dock
neighbors (who don't read manuals) insist Garmin is the most user-friendly. (They also haven't used anybody else's products, so the comparison is a little shakey.) Just the other day they were waxing eloquent about how they could get a "chip" from Garmin to update their charts... seemed surprised that I could download chart and software
updates and do all that similar updating on my system without a "chip"... but they also admitted that they don't know enough computer/systems jargon to even understand the directions on how to do stuff like that themselves. (And they didn't know any technical names for their "chips.") Near as I can tell, from helping one of those bubbas figure out how to save tracks and how to create waypoints/routes (since he doesn't read manuals) on his non-touch-screen but relatively new (I think) Garmin system... it was easy enough, with manual in hand. I didn't see much difference in the mechanics compared with my system.
I'm not a fan of touch-screen-only. When underway in choppy seas, I can't be trusted to press the right point on a bouncy screen
I tend to agree with your point #2 (one company) because most system and network issues I've encountered in the past 40 years -- not just with marine electronics
but with computers
and connected devices in general -- seem to be more easily resolvable when vendor or manufacturer A can't blame it on vendor or manufacturer B or C or D or etc.
Seems like makers are now offering more options on charts, especially vector. Although I tend to use raster charts more often, we can use NOAA, Jeppeson (C-Map) or Navionics vector charts too. I think Garmin and Raymarine currently offer similar options.
When we did our last upgrade, I didn't directly care about brand... but wanted to salvage
the existing radar and a DGPS unit. They were by Furuno, so the rest of the upgrade is Furuno (with the exception of ICOM
radios). It happens that their NAVnet
3D was the latest thing since sliced bread at the time, AND the computer-based MaxSea
counterpart was available for backup and planning... so that's what I chose... and I've been very happy with it.
I do more and more appreciate the ability to show different stuff (sensor output) on different screen
real estate depending on circumstances at hand. The idea of multi-function displays (to use Furuno's term) works for me, and I'll be tempted next time (if my radar craps out) to replace the radar display and a fishfinder
with two MFDs. I still usually prefer to usually dedicate a screen to radar, but the versatility to do otherwise when useful (and to overlay radar on the chart) is attractive.
Time has passed; don't know what's the latest and greatest these days.