With the greatest respect, Cannonball, I don't agree. All magnetic couplers are not equal. The only ones I've found to work reliably are the body-mount Micro-Trains ones, part 1041. They can be made to fit on almost everything except for really weird locos and very long (70+ foot) cars, where you need truck-mounted couplers only if you have small radius curves. Every single one of my locos and cars I've swapped out whatever was on them for 1041's, and they work beautifully and reliably for hands-off switching and for continuous running.
There are five capabilities needed for a coupler to work properly: (1) it needs to stay connected going forwards over an uncoupler, (2) it needs to stay connected going backwards over an uncoupler, (3) it needs to connect when two bump together, (4) it needs to uncouple when pressure is released at an uncoupler, and (5) it needs to move aside and stay uncoupled when two bump together over an uncoupler. Unless the couplers can do the appropriate thing at each of these five points, 95% of the time (that is, 1 in 20 times you will need to try again), they are a pain in the butt to use.
The Atlas ones don't disconnect properly, and many other MT ones have the slinky effect and make a real mess if you're trying to run continuously. MT truck-mounted ones are tricky to do switching with as they often don't reliably connect and disconnect and easily cause derailments as they produce uneven force on the wheels going backwards through switches. Kato ones aren't designed for uncoupling.
MT make all sorts and I don't really know why. For example there is a special one for the Kato F7A loco, but I found it very loose and unreliable. Saw off the old one and put a 1041, it fits fine.
So, whereas I used to be selective about what I bought, now it's easy. I'll buy any old car or loco that I like the look of, knowing that I'll chop off the couplers and put proper body-mounts on and swap the wheels for lo-pros.
Once you get into the swing of it, making perfectly working lubricated MT 1041's from the bulk packs takes less than a minute per coupler.
Charles