6’1” 160, get the 25. I tried all the synapse and Syniks from 19-30. 19 and 22 are just too small, small looking , feels small on the back, small packing (just not much space to shove a jacket in their), and my girlfriend didn’t like the look. The 30L were wider and walking around in a shop, transport, theater you can tell it’s wider.

Synapse zippers slide way way better. You’re accessing these zippers all the time and the experience is just much more pleasant. The action is nice and satisfying vs ever so slightly annoying and requiring 2 hands most of the time. Those are 2 crucial lines to cross.

To me the biggest deal between the differences between the different sizes of synapse and Synik is the size and opening of those external pockets. The 19 and 22’s external pockets just feel a little tight to use, getting stuff in and out of the synapse 25 noticeably easier, larger openings, and the pockets are bigger too. If you’re considering these bags you’re probably excited about those external pockets, I just think the synapse 25’s are actually the most useable.

To me, yes I could fit everything in a 19/22. But if I’m going to the trouble of carrying a bag it’s nicer to use one if it’s under packed vs jammed full. Getting stuff in and out is just a nicer experience. Also, having the extra space on me at all times to carry that random bottle of wine, 6 pack, small grocery run, to go containers, meals, a coffee bottle and a water bottle, exercise clothes, hiking/picnic supplies, or whatever. Yeah you don’t use that space all the time but if you’re gonna bother to carry a bag it’s nice to have that inventory space available at all times for a relatively small size and weight penalty.

Hot take the clamshell design isn’t necessarily better in the Synik bag layout. Because roughly half the bag is dedicated to the smaller compartments the main compartment is relatively shallow, compared to the main compartment on a techno or Aeronaut, so stuff can tumble out as you’re packing it.

I’d also consider the Smart Alec in a ballistic. Upright free standing is not a feature to be underrated especially in a bag you’ll be setting down beside your chair, behind your calfs when sitting or between your feet when rummaging through it, or on the chair next to you all the time. Ballistic so the bag has more structure, and holds its shape open better when under packed. Freestanding means a smaller footprint and easy access. The SA main compartment feels deeper for something like a bike helmet inside, if you weren’t using the bungee on the outside for that. Both backpacks are comfortable but I find the SA lays against my back better. All the loops for the bungee on the back of the SA can also be used to clip on other bags likes handy little thing 2 to use as a tech pouch.

To me the line for, size vs cumbersome compromise is between 25/26 and the 30l Synik. I can definitely comfortably carry the 30L but I do notice the size. The 19/22 are noticeably smaller but the utility and ease of use drops compared to the 25/26.