I'm not an expert, so someone can certainly give you better insight than I can. Seeing as how no expert has responded yet, I'll give you my thoughts in the meantime as I have run both Gen 1 Helixes (but have been in boats with the Mega Gen 2) and Gen 3 Lowrances.

The MEGA imaging on the Helixes are the clearest and most detailed down imaging and side imaging that I have seen. It is noticeably better than the Gen1 and the Lowrance at this time. That's a big advantage. The other advantage is that you could link to an Ultrex if desired (not high on my list).

The touch screen on the Lowrance units is the biggest upside over the Helixes that I see. Much easier to go through your menus. Much easier to specify what kind of marker you want to use for a waypoint, labeling them, etc. Also, on the Lowrances, if I put a "tree" waypoint out, it always shows up as a tree on the screen. On the Helix, if I put a tree, it just shows up as a run-of-the-mill waypoint unless I actually move the cursor to highlight that specific waypoint. Maybe this is different on the Gen2's and maybe there's a way to avoid this on the Gen1's and I just haven't figured it out, but it's annoying.

The best of both worlds may be the Solix as you get MEGA imaging and touchscreen, but dang those are expensive.

I'm sure there are some other differences that I just haven't dug down deep enough to see. Maybe someone else can point those out. I doubt you'd be disappointed in either--small differences from what I've seen.

If you're not interested in linking the units together, you don't need the G2N, just the G2. The 'N' means that it's networkable