This section seems to have slowed again, so here we go.

What is your go to thread and why.

As for mine, thread is UTC 70d 8/0 or 140d 6/0 for ties from 18 - 2/0 and the majority being near the middle.
I like it because I can twist it for a more cord like wrap or untwist it for a flat wrap or split for dub loop.

Trying to get a feel for who ties what and realize trico flies and classic salmon require lighter thread for less build up ie 17/0- 24/0
and large salt bugs use large thread ie 3/0

Over the past year or so, I've used Danville 70 denier probably 90% of the time.

I started using it for similar reasons to your comments, it can be spun and flattened. I just got used to it and ended up using it for most of my tying.

I also used that thread years ago, that is what the shop bought for us to use.

Do you use waxed or unwaxed and did you use that to tie the last few very nice classic style you posted ?

Last time I tied a classic I used a silk but that was long ago may have to try again someday.

On #14-#22 8/0 UNI thread on #22 and smaller I go with Veevus 14/0. For #12-#8 I use the 6/0 UNI thread on trout flies. For clousers and saltwater flies I like the UTC ultra thread. On really big salt water flies 3/0 UNI thread but have sometimes been using 240 denier danvilles flat waxed nylon.

On classics I like pearsals silk but I haven't done any in a ver long time and when I did them I was doing flatwings like the grey ghost and spruce.

Yes, I have been using it for the Salmon flies that I have posted. I have the waxed version.

I have also used Veevus 12/0 thread and it is really nice. It is small enough that you don't have to flatten it. If I ever run out of the Danville I may switch to the Veevus.

I do use heavier threads for deer hair and for larger buck tail patterns. But, I just use what ever brand I have on hand in the right color. I don't tie enough of those patterns to go through much thread. So, I don't have a preference.

UTC 70&140 along with some Veevus.

I have had so many bad experiences with terrible quality control from UTC (thread knotting on the spool, being wrapped on unevenly, etc) I switched over to Veevus last year and couldn’t be happier. I mainly use their 140 Power Thread, 8/0, 10/0 and 12/0.

I use embroidery thread from Joann's. Black. Why? It's available locally. It's strong. It's low fuzz, and makes a beautiful finish.