The 1281 is the square I use the most - for marking and checking square.
I do own the Story Stick. However, I have never used the full length of it for anything. I almost always use the first section for cabinets and other pieces where I want to duplicate a measurement. All the extensions were a waste of money for me but maybe if you do a lot of plywood work the full 96" may be useful. I don't do that type of work.
I also own and use the Pocket T-Squares (all 3 - 3", 6", 8") for marking. I find them very useful with a 9mm lead for marking a specific distance along the length or width of a board.
I own a 6" Carpenter's Square and do find it useful, but I use the 1281 much more often unless I need a smaller square to fit inside.
Other than that, I do own other WP stuff but it's kind of a luxury. I own the WP MFT Square and feel that it's one of those things I bought, use all the time to check the squareness of the miter head on my MFT, and then feel completely confident it is square. Could I get along without it? Sure, but I love the confidence it gives me when I use it just for that purpose.
I own some other WP stuff, but these are the tools I use the most.