I'll go for a Garmin GPS over other brands, I would recommend the 64's series Model over the 78, as they have the better battery life, I have both a 60CSx and a 78SC and I get at least 40% more life out of the 60 than the 78, both have pretty much the same features. I'm getting about 12 to 14 hours of life with standard AA Alkaline batteries, where I'm getting 18 to 20 hours with the 60SC
The only advantage is with the 78 is that you can buy it with preloaded (full version) marine charts rather than having to buy the charts seperately and that with the 78 you can also insert the micro SD card with Topo maps and switch between the two. Unluckily the 64's currently on-sale that come with preloaded charts are the Lite version of Topo Maps (40m contours) not the full version of Aus/NZ Topo V5.
I also use a Samsung tablet that has a full in-built GPS and ability to access both Topo and Marine Chart apps, My Samsung tablet doesn't need access to cell phone towers to assist with location (but it can), from memory it can access over 14 satellites, not as good as a full blown GPS which can access both GPS and GLONASS networks as the current model Garmin GPS. I research into the apple range of tablets lead me to believe that they rely more on being able to see the cell phone network,rather that the GPS satellites to give a position.
As for the current Garmin software, I find that the ulility of the older model Garmin better than current models.