What to wear between base and midlayer?

cotton is only an issue because it isn't as warm and if you sweat in it, it'l freeze ya later. if it's between other stuff and does the job and you're not sweating on it, you're fine. sometimes a long sleeve cotton t shirt is just what i need to add as a layer

Just buy a cheap hunting fleece from 2nd hand shop

It normally takes some playing round to find the right warmth midlayer.

On 99% of days I rock under armour base + shell jacket/pants
On coldish days I rock a haskill midlayer with the above
on ridiculously cold days I rock the hunting fleece instead of the Haskill

That is totally up to you my dood. I wear a variety of layers depending on how cold/ windy it is. If it's really cold sometimes I do wear a thin fleece over my base layer and under my puffy. Sometimes I wear 2 base layers or a t shirt and a base layer over it or sometimes a wool shirt over my base layer. Vests are good too wear one over or under your puffy whatever. My homeboy rocked a pretty nice looking wool sweater as a layer the other day and it looked like the sort of think you could wear to church in the midwest but really seemed pretty ideal.

SofaKingSickcotton is only an issue because it isn't as warm and if you sweat in it, it'l freeze ya later. if it's between other stuff and does the job and you're not sweating on it, you're fine. sometimes a long sleeve cotton t shirt is just what i need to add as a layer

That's basically what I was thinking. Just wanted someone else to confirm it. I have different fleeces and wool for colder days. I also hate walking around in a baselayer if I have to run in the gas station or something on my way there so I like having a shirt on.

All else equal stay away from cotton. Merino or synthetic.