I've struggled with this at times as well, especially on projects where the next action can change depending on the outcome of a previous action.
I'm using Evernote now, it's not perfect, but it works for me as long as I'm disciplined enough to keep things simple. For my NA list, the title of the note is the next action. If an action is part of a definable chain of events, I can list the subsequent actions in the body of the note. When I complete the first, I cut and paste the next out of the the body into the title. Yes, I loose my history of completed actions, but that isn't all that important to me.
For many actions, I know there is a followup action, but I don't know it is. For those, I can either wait for the weekly review, or just create a new NA "Determine next step for ..."
I might have other support info in the body of a NA note as well, like a phone number, support incident number or the business hours for a place I need to call, but no more than that.