It’s nice that BMW offer us the choice I really like them both. I thought about them and went with the Adventure but could have gone either way. The biggest complaint with my previous GSA was the heavy feeling front end most noticeable at low speed. I can say the GSAw does not have this issue.
With it's wide front, upper and lower bars, big ammo can luggage and racks, I've always felt the GSA’s to be a bit too "Rambo" looking for my taste. Plus this current one is listed as 48 pounds heavier. Then again the regular GS has it's own styling quirks, the radiator fangs in particular. I prefer cast wheels which unfortunately don’t come on the GSA.
The GS's vario luggage when collapsed looks better than the GSA boxes. And a GS looks great with vario’s off because the big ugly brackets are absent. Opened up, the Varios are larger than Adventure bags but only hold the same. As far as function and usefulness there's no comparison, top-load bags are easier to fill and effectively hold more than side-loaders.
With side load bags the right side is the most convenient to use since it’s angled up when on the side stand. But since BMW moved the muffler to the right that is now the small bag and especially when collapsed it’s difficult to fit things in and get the lid closed because the bottom is only 3" inches wide.
I would have preferred Jesse's which are narrower but I went ahead and bought the Adventure bags since the bike came with the mounts. For short rides and day trips they stay off anyway, I pack my stuff in a soft bag that rests on the rear rack and seat (I will probably convert to a solo seat.) For longer rides and camping trips the big, ugly, practical, aluminum boxes go on. Once at the camp site they function wonderfully as an ice chest.
The Adventure's large tank is nice to have sometimes. Actually if you only fill it with 5 gallons like a GS holds, and the GS has crash bars, driving light mounts, etc. like the GSA comes with, there’s probably only 25 pounds difference in weight between them. I find the GSA more comfortable with it’s taller seat and a little more suspension never hurts. I also like the off idle power delivery with it’s heavier flywheel effect. Windshields on the GSA and GS both work fine for me, I usually just leave them down except in rain. In rain the GSA's larger shield and wingletts do offer more protection though.