Best To Do List and Calender App?

I’m fully aware that productivity is one of my weak points and need to improve it. I’m reading Chet Holme’s Book – The Ultimate Sales machine at the moment and he talks about 6 simple princples to improve productivity:

• Touch it once.
• Make daily lists of the six most important tasks to accomplish.
• Plan how long each task will take.
• Assign time slots for accomplishing each task.
• Focus on the difficult projects first.
• Ask yourself, ‘Will it hurt me to throw this away?”

I’ve made my list for tomorrow. Step by Step…

What’s the best way of keeping on top of to-do lists and scheduling?

Trello? Google calenders? Evernote? Something else? Chettime.com?