I want things held rigidly (mostly). The articulated holders, especially with the fluid lock balls, move around too much and the post and joint ones with the alligator flips require constant tightening. (Those third hands w/ the Magnifier are the horrible)
I use the AliExpress (AE) board holder which rotates; buy a longer piece of AL channel to make it longer if needed. I often lay it down, so the board is close to the bench so I can support my hands. The question in watchmaking is "Are you Superman?"; Reply "Huh?"; response:"Why are you trying to do it in the air?" (IOW, support your hands and arms).
I also use a $3 AE mini vise (the gray one) which is crap out of the bag, but great if you have a mill to cut a channel into the closed jaws which gives you a reliable surface for holding the small boards.
I also use naked alligator clips when soldering on my Si mat (cut from the large mat which I find to be a PITA).