This looks very promising! I've been using MenuMeters for quite a while, but El Capitan breaks them, and the author states no future fix may be available. I then tried iStat Menus, which is a nice utility, but a little pricey for a monitoring tool. I've just installed MenuBar Stats, and have only played with it for about five minutes, but I'm already thinking about ponying up the $4.99.
In the interim, I installed Trend Micro's free Dr. Cleaner, and it has features not present in MenuBar Stats, so I may continue to use DC for memory and disk cleaning and MBS for CPU, Network and Disk monitoring.
I need to play with the prefs a bit more to see if I can't work them into something personal, but the sense I have is that MBS is already 95% of the way there. Nice!