I did a little research because I always wondered what the big difference is between 3l and 2l and found a very technical description. Ill save you guys the reading and it just comes down to the 3L being more durable and having more breathability in really instense conditions. The 3L will also feel and sound crunchier
If I were you I would probably just go with whichever model has the better look that I like because all AK gear has a lifetime warranty. Unless you do splitboarding or BC riding the 3L is probably overkill
Sounds like you've read the goretex website and never touched the various materials, they are quite different.
3L is professional grade material, (pro shell or soft shell) on the hover pants and jackets. Very tough material, much thicker than the 2L fabric, and yes its a little crunchier. I have a full outfit of 3L proshell, and last year I got a 2L jacket out of a deep discount rack, it was so cheap I bought it even though I had no use for it. 3L pro shell feels like it will last a lifetime, while 2L feels like a windbreaker in comparison.
The other fabric that is labelled 3L is in the freebird jacket - it is goretex pro stretch rip stop 40D. This is a completely different gig. It's way lighter than 2L or 3L, feels almost delicate. If you have tons of dough and want to have an ultralight superbreathable shell this is for you, you can stuff it in a tiny backpack and wear it for heliboarding in golden powder where it won't suffer wear.
So 3L pro shell and soft shell is top of the line with focus on durability, while pro stretch focuses on ultralight weight performance. That said the 2L stuff is good too.
Since the OP seems to fund his outerwear off an erratic bonus program I recommend the durability of 3l pro shell to get him through till those cheap bastards pay another bonus in 2017.