Welcome. I am 6’3” built somewhere between dad bod and CrossFit guy.
Both will work fine. Kuiu inseams are like 34 inches. Sitka regular length pants work fine for me. My tops run from xl to xxl in most clothing. Like ledd slinger I had to size up some kuiu stuff to get the right fit and room to layer. My dcs guide jacket is xxxl. Overall, I have found kuiu sizing to be a bit wonky and inconsistent. Sitka is adding more tall sizes in their tops and I find their overall sizing to be fairly consistent across their line.
I have a bias for Sitka but both are fine. At this point the only thing I still buy from kuiu is bottoms. Their zip off merino base layers and hip vents on their pants are the bees knees.
Kuiu CS was a bit underwhelming the time I needed it for a pair of pants that didn’t perform as advertised (no dwr, froze my ass off). Ultimately Jason (RIP) stepped n and overruled his people and got me a refund. Sitka CS has been stellar on the one time I used it. They went above and beyond to replace a set of gaiters and they are super responsive when I have asked a question.
+1I think since this is in the clothing section, he is referring to clothing not back packs.
I have a bunch of new Kuiu clothes waiting for me to try when I get home tomorrow. Reading reviews, people say most of their clothes run a size small so I ordered XXL in place of XL on the Guide DCS jacket and Guide pants. The Ultra merino line reviews say they are true to size, so for those I ordered XL. I'll let you know what I think about the fit and quality when I try them on.
However, I do also have a new gen Kuiu Pro pack waiting for me with the clothing if interested in that as well.