I like Apt cause it has a lot of good tools in both cli and gui. Other than that I've only used rpm briefly, and compiled from source. Source is what it is. I wouldn't want to run a whole system that way. rpm didn't seem as polished, and I thought the tools were a bit lacking. That impression's just from brief use, and it was awhile ago, so that might not be accurate.
I forgot, I've also used boutique package managers on micro distros, but I don't have an opinion one way or the other. They did the job, and I don't expect much due to the nature of the distro.