After trying lots of different programs over the years, I have recently started using Todoist and am starting to enjoy using the program. It is not a traditional calendar app, but more of a way to just get all your thoughts down in one place. You can schedule events and set it to remind you via text message, email etc. I bought the annual service "Pro" plan and use the iPhone app as well. Everything syncs instantaneously.
Best feature is its natural language parsing. You can type in (or use Siri) "Bank of America credit card payment due every month on the 20th" and it will automatically set up an entry "Bank of America credit card payment due" and schedule it on the 20th of every month. No other button clicks necessary. Crazy world we're living in, eh?
What do you use to keep up with all you have to do? Is it analog or digital?