merino is warm when its cool and cool when its warm, and being naturally antibacterial doesn’t smell if repeatedly worn without washing (eg. trekking/camping).
It doesn’t wick like synthetic so if you are a heavy sweater avoid it as it will hold on to moisture, and then you will get cold when you stop exerting yourself.
I’ve seen detractors on here refer to “Emperor’s new clothes” but Munqe Chick and I must own more than 20 merino tops between us, ranging from budget Planet X and Aldi base layers to premium Rapha, Howies, Vulpine, Finisterre etc.
And if you dare wear Howies at the same time as Nike you will cause a tear in the space-time continuum…