I have a variety or loupes, magnifiers, microscopes, including a Shure SEK, and digital scopes. For routine checking of muck on the stylus, and general state of cantilever, I found a 7X magnifier to be the best for my aging eyes. I got one with a Mint protractor for one arm, but the lighting was intermittent, and bought another one of the same power which seems to be a little more robust. It was cheap. I’m using these to inspect whether there is any build up on the stylus and to make sure the cantilever is straight. This is not meant for examining stylus wear. I run good cartridges, have gone to great lengths to develop a record cleaning regime, and try not to obsess over it.
Currently run a Koetsu Tiger Eye in a Kuzma Airline arm on the main system.
My second system (vintage) involves a little less compulsive behavior, but have a similar assortment of loupes and magnifiers in that set up.