I have two pieces of Minus33's lightweight merino wool, a t-shirt and one of their 1/4 zip pullovers. They're well-made and of good quality. My only complaints would be that they offer far too few color options (for bottom layers, this is obviously a very minor issue) and I was led to believe their sizing was 'loose fitting' but in my experience both pieces fit very snug, almost like compression items.
I own a First Lite 1/4 zip in ASAT camo (the Chama I think it's called, I forget) and it is much heavier than my Minus33 1/4 zip; I'd call it mid-weight. It's very high quality, fits extremely well (and stretches to allow lots of other items underneath it as I've worn it as an outer layer over sweaters as well as a base layer; always retains its shape); has the thumb holes at the ends of the sleeves. I'd definitely buy more of their items, but for the time being, I simply don't need any.
I also own a pair of the First Lite Gila pants. These are a bit thinner than I expected and they weren't kidding on their website when they stated they're an 'athletic cut'. I normally wear Large BDUs, but I bought a used pair in XL that still had tags on them. They fit, but they're very snug all around. I don't know if I'm going hunting or to the disco. Not impressed with their pant design; if you order any, be certain to get at least 2 sizes larger than normal.
Hope this helps.