I can tell you what I've found works very well, peat pellets. You let them absorb as much water as they can, put the cuttings in, keep them in a chamber with a 40w replacement LED bulb. Two or three days later I water with a light hydro solution, enough to rinse them out pretty good, throwing away the runoff.
Constantly wet is not a good situation for cuttings because as you've seen they tend to rot. Another good thing about the pellets is that they reduce transplanting shock, since much of the roots are safe inside them. They tip over less too because the pellets stabilize them somewhat.
That's all I ever use now for cloning, peat pellets, they work perfectly. They include a small amount of fertilizer in them, and are pH balanced, so it's not as acidic as plain peat. That's also why I water enough to rinse them out good. Probably wouldn't actually need to add hydro fertilizer, it's just what I do personally, more complete than what they put in there.
