I’ve used a variety of stitch markers but was wholly unsatisfied with what’s currently available. They’re either bulky or intrusive or too easily dropped/lost, all of which are frustrating. I’ve worked out a couple solutions that work better for me.
If I leash together two of the commercial markers (I’ve used plastic split ring, round plastic and triangular) they work much better as the marker doesn’t get lost and is easily retrieved if it slips from my grasp when transferring from one needle to the next, but they’re still bulkier than is comfortable when using sock yarn and size 1 needles. On the plus side, if the leash is tied to a clip or pin so it can be fastened to the work, they don’t fall away when they’re dropped.
An even better solution are markers made from filament and beads. The flexible filament is very thin and keeps the marker from interfering with the work, the bead makes the marker easy to spot and acts as a handle or connector and are big enough that both needles can simultaneously be inserted into the marker reducing the chance you will drop it when transferring between needles.
Beyond that, they’re pretty and make me smile.