I have flown planes with push buttons and from a safety stand point they are not a good idea. There is no key to lock the aircraft's ignition. Anyone can get it the plane turn on the master and push the button.
I am reminded of SnF a few years ago where a customer was sitting in a light sport display plane and said; "What does this button do"? The Rotax 912S engine started full throttle, plane shot across a busy area, hit a ditch, went airborne, and then crashed into 3 cars.
Push button stater? NOT a good idea in an airplane.
Go with the key lock. When the key is on dash or in your pocket the plane cannot be started.