What is the best to do list ?

I seem to constantly morph my requirements of a to do or reminder list for work.

When things are quieter (rare these days admittedly) I try to run a wholly electronic system. usually based on my reminders app on the iPhone/iPad that replicates through to my 2 Macs. However as things get busier I tend to devolve back to paper - I have now a regular to do list that segments off types of task (Call Backs, sales chases, marketing, urgent, low level etc but even that goes by the wayside when I'm super busy and I have two sheets - one urgent, one everything else.

Not very efficient or technology based but seems to get the job done.

The problem with the two sheet method is I do tend to lose the planning and stop thinking strategically so for example, usually I work on marketing five days a week (and both the phone and single sheet To Do methods support this quite well) but last week having reverts to the two /panic' sheets method I only managed to get two days worth out - whether this is a function of the system or the lack of time that drives me to that poorer system is a valid question - going to force myself back to a more logical and less rushed approach this week and hopefully the marketing will get back to normal.