I'd like to get some recommendations for what other painters think is the best magnification system. What level of magnification is good for painting IA scale miniatures. I'm sure the more the better, but I'm just interested in what others use.

I picked up some of these a few months ago, and they were worth every penny (only £14).

https://www.amazon.co.uk/gp/product/B01M10NFSH/ref=oh_aui_detailpage_o09_s00?ie=UTF8&psc=1

I had a mag-glass with clamps , but I need to move the mini about (my hand also shakes, so I rest my hand against my desk) so these were perfect for being able to move about with.

Its made a massive improvement on the quality and accuracy I can achieve. I tend to rely on the 3x magnification

Oh, thank you. That's a great idea.

I use a magnifying visor. Look for Rolson Magnifying Visor (with a LED lamp).

(You can choose1.2x, 1.8x, 2.5x, 3.5x and also combine them for more magnification. The 1.8x and 2.5x have been enough for me.)

I've tried a few different visors and I've never had success with them. The magnification is good with them, but they were either uncomfortable or unstable for my head. The whole rig would rotate forward unless I made it really tight and then it became uncomfortable. I'm sure other people don't have this problem, so it's fine for them. The solution I found that works best for me is a simple set of clip-on lenses for my glasses. I've used these (2x mag) ones in particular for over a year without discomfort.

I use a visor from harbor freight. Works really well and is comfortable.

https://www.harborfreight.com/magnifier-head-strap-with-lights-38896.html