I personally only have Legacy at home, and have no plans to control via tablet or phone. But I will use the LCS items with my Cab-2 to throw switches and turn power on and off on spurs.
With that said, and the fact you are only looking at MTH or LC+ locomotives, I would go DCS so you have 1 remote to control all MTH locomotives and track. I wouldn't worry about LCS unless you plan to also get Legacy locomotives. Then I would do both DCS and LCS.