Todoist is one of my favorite tools. Even though there are a few things that I don't like about it, I just can't seem to leave it. I have had the premium version for a number of years now and it keeps getting beter.
The use of filters and labels makes this a tool with endless possibilities. The fact that the app looks the same on every platform is a big plus and has low overhead use on cpu's is crazy good, no searching around and figuring out where things are – just get it done!
One of the most dependable and useful tools that I use on a daily basis.