UNIQLO Heatech any good for keeping warm or stick to merino?

[Milomonster]

Heading to NYC over Christmas and want to buy a warm layer. Anyone used Heatech to keep warm? Are they breathable? Trying to decide between this and merino. TIA.

The Uniqlo does keep you warm but I find it’s a nasty sweaty heat. I also find it makes me smell and it’s difficult to get the smell to wash out. I’ve got some because I couldn’t afford anything better but if I had the cash I’d go for merino or silk.
I’ve bought Uniqlo and merino for my daughter and she prefers the merino.
Saying all that I know people who swear by the Uniqlo so maybe it’s just me.

I haven't had sweaty issues with the heat tech, and it is a decent underlayer - very thin/good insulation. I sometimes wear a heat tech top under a shirt or a thin knit jumper.

However.

If I could afford the same stuff in silk or Merino I definitely would. In the past I've bought silk underwear from Patra and loved it (the non-underwear clothes aren't exactly my style though), wash on the delicate cycle and it definitely lasted long enough to make it worth it.

Just seen the replies. Thank you for sharing your experiences. I think I’ll get merino.