I have the 'Best Friends Bareback Pad' I love it, it's really comfy for you and the horse, but still lets you feel lovely and close. It doesn't slip, as long as you don't leave the girth too loose (although, you don't have to tighten it as much as an average saddle) And it is stirrup-free! It also has a strap on the pommel (well, where the pommel would be on a normal saddle) to grab on if your horse suddenly gets fizzy / spooky and you start losing you seat!
I don't know what it's like in comparison to any other bareback pad, as I haven't tried any others, because this one has lasted me years, and I'm very happy with it, and not looking to change it any time soon