In the rush to get all the 'new hotness' items, many people seem to forget that the old stuff still works just fine.
I ran the same Daniel Defense V3 I got back in 2011 with an aimpoint pro, Tory BUIS, VCAS sling and magpul furniture until just a couple years ago. And it STILL has the same sling, BUIS, and furniture on it, despite other changes.
The only REAL differences, in large general terms you're going to see from your day til now is, better selection of handguns, pistol-brace-everything, RDS on handguns becoming more prevalent, 1x6/8 ruling the rifle optic market, budget optics have come a LONG way (holosun/Primary arms) and everything is now Mlok instead of Pic rails, for which, frankly is the ONE thing I am thankful for. I'm frankly not seeing a pic-rail comeback, unless there's some weird instagram-driven retro "thing" going on kinda like ACU in the airsoft community a while back... :laugh: Mlok is the truth. Oh, and lights are now hella bright. #allthelumens :cool:
That's pretty much it, as far as big obvious stuff.
Surefire/Streamlight are still go-to for WML, the big names in optics/rifles/handguns/accessories/etc are still the big names. Apex triggers are still the shit (make sure you get a flat trigger for extra instagram points).
Pretty much the only thing you need to make your rifle a "current year" gun is swap to Mlok and stick a LPVO on top. For handgun, slide cut for RDS with lots of cool but needless serrations and cutouts, swap to a flat trigger, mount a Holosun. Voila, now hip with the instagram kids. ;)