As others have stated, Merino wool is a great product for a base layer, however there is nothing wrong with wearing synthetics during certain situations.
For example; synthetics will do the job if you’re taking short hikes to a morning or evening stand without building up a sweat, or if you’re not going to be around an open flame.
I use synthetics and Merino wool base layers and as Canyon stated; silk does a nice job as a base layer under wool.
In regards to the different types of Merino wool base layers that I have or have used; Icebreaker, Ipex, Minus33, Woolpower, Filson and Kuiu, the first three manufactures make a very high quality product. I purchased the Kuiu because it had a camouflage pattern, however I find the Kuiu Merino (250) wool course and scratchy, and the zipper support material irritating on both the 185 and 250 Zip-T’s.