Waste Management (WM). Solid long term DCA stock?

I posted a week or two ago that I'm expecting a promotion and will have extra money to divide into an additional stock or two alongside my existing portfolio. (KO, BRK.B, JPM, AXP, MSFT, GOOG). I've narrowed down AMZN as a definite add once I have additional money for monthly contributions. It's a great company. I've also been considering a few others. One company that I wasn't aware of that I have started researching is Waste Management. It seems to be the epitome of a boring compounding machine with a big moat. The exact kind of business I like to (think) I look for. Anyone in on WM? What are people's thoughts?