DaisyDisk is still my favorite disk storage management tool. I've been using it for years with zero problems. The application has the best user interface of any disk management tool I've ever used. Not only is it attractive with its concentric circles, it's also the best way I've ever seen to convey disk storage information. Now that we all have SSDs in our Macs, this is a handy tool on your belt.
Recently the App got a rewrite that dramatically improved the scan speed and gave the user interface an El Capitan-friendly paint job. Best of all, it's half off, just $4.99, now through Monday.