@pwjone1: Thank you for starting this thread and all of the research you did and contributions from others that you inspired.
After a lot of reading in this thread and a lot of my own research, I settled on Checkmark Pro. It is the closest I was able to find to ListPro which I have been using for almost 6 years now. Specifically, I was looking for an app that allows you to create reusable lists with the ability to flag & check and "show/hide flagged only" and "show/hide checked only".
One disappointment... Checkmark seems to only allow you to show/hide checked or show/hide flagged. It does not appear to allow you to use those options together (in combination). For example, show flagged only
and show unchecked only. I used to use ListPro this way. I would flag all of the items I wanted to pack for a trip. And choose "show flagged only" to hide all of the items I was not planning to pack. Then I would choose "show unchecked only" to make things disappear from the list as I packed them and checked them off the list.
Another disappointment... I miss the ability to synchronize between my PC and my mobile. I have all of my lists in Checkmark on my mobile phone. But what if I lose my phone? Then everything is lost. I know that I could do backups of my Checkmark database. But remembering to do that every few months instead of just having automatic synchronization to a desktop (or web-based) application is an inferior solution IMHO. Checkmark has the ability to synchronize to Google Calendar. But since I don't use it as a ToDo list, I don't put dates on the list items. And without dates, I do not believe they will sync to a calendar. I use this as a List Manager (grocery list, packing list, movies I want to see list, etc.) not a ToDo list.
If anyone has any ideas of an app that supports list management in a similar manner to ListPro and also has synchronization to a respective desktop or cloud-based app, I'd be very curious to hear about it. For now, I will continue with Checkmark and dream about ListPro developing an Android app. Thanks everyone.
Brian