I've found I do much better with pen and paper when it comes to taking and keeping notes and todo lists. I get SUPER picky about these things, but have found a system I like.
Notebook:
https://www.amazon.com/gp/product/B00BBNNSTU/It's big enough to hold the essentials but small enough that I can't go overboard stuffing it with supplies. The cool thing is the binding can be opened, so you can rearrange the pages, or add a custom combination of page types, or just remove full pages for archival. You can buy refills with the same openable binding, but the combs are a bit small. I use the pages out of these notebooks just because they're more economical:
https://www.amazon.com/gp/product/B00BBNNSTU/ I added the covers from one of them to the notebook so that I always have a solid surface to write against instead of the fabric cover. I keep lined pages in the front for to-do lists, grid paper in the middle for general sketching/notes, and more lined paper in the back for journal-type entries. Being able to rearrange pages is really nice and makes this system work quite well for me.
I keep a pen and pencil (both Rotring 800) in the outside pen pockets, and the flap top has a clickable eraser, one highlighter, and a couple of extra pens and markers. I keep a small ruler, triangle, eraser shield, and some post-it flags as well. The Rotring 800s are very nice all-metal construction, and the entire tip of the mechanical pencil retracts to keep it and the notebook safe from damage. They often go on sale on Amazon for ~$25, which is still expensive, but much more palatable than their normal $60 price tag. Still need to get a better refill for the pen, the stock one is ok but not amazing. Here's the contents:

Eraser:
Uni E-Knock(Discontinued?

)
Backup pencil:
Uni Shift Pipe Lock Retractable mechanical pencil
Backup pen:
Zebra Sarasa Grand with Signo refill
Alt color pen: Pilot G-2 Red
Generic highlighter
Sharpies
Eraser Shield
3" 45/90 triangle
6" Machinists scale
Post-it flags.
I'll probably eliminate the sharpies since I always have them around anyway, and I'd like to replace the ruler and triangle with nice plastic ones that will be less hard on the notebook, just haven't found ones I like yet.
Just to prove it all fits nicely:

Edit: So we have the "expandable thumbnail in message" options for attachments now, but they don't work?