I have an arteryx phase sl long sleeve, probably the only non merino base layer that that I've tried that doesn't reek after a couple of hours (I've never actually tried merino though too expensive), I've worn it for 2-3 days at a time in Ecuador, not overnight hiking but with some day hikes of 3-5 hours. The thing nver stank on me. Another good thing is that the neck actually goes up to your neck.
Anything i've tried from patagonia has a massive neck, even their UV50 stuff which seems to defeat the purpose for me, they stink after an hour sitting around at home and most people I now would say I smell neutral, I don't even really need deodorant if I'm not wearing a suit.
Arcteryx does not have a UV rating and it seems it's made of a mesh, even so I never got burned even in direct sun at the equator. I also wear it for bike rides (up to 100km). One thing to note is that they are slim fitting, I normally go medium sizes (I'm 6'1" 170-175 pounds) but found the medium too revealing around my skinny fat gut. A large doesn't hang off of me. Unless you're comfortable with the stretched feeling on your stomach or you've got a six pack or a very flat stomach go with your regular sizing if not go up, .
It seems the phase sl has been "revised" I guess that's their way of raising the price and now it's about as expensive as merino but it's lighter, more compact, washes in the sink and dries fast (wear it damp and 10 minutes in the sun it will be dry). I have a few "running" long sleeve shirts and 2 or 3 patagonia shirts, I never wear them now. The phase sl is very light and the sleeves seem to be starting to fray a bit and look a little stained but so far no holes (after one season).
I have a skinny neck and wear a junior buff around my neck, along with shades, long pants and a hat I never burn now except for my hands. I burn really easily and I hate applying sunscreen all day so this has become the best solution, although my girlfriend's pretty mortified to be around me in this get up . . .
Wow I really sound like an ad, but for me it works. Sorry for the long winded message.