Pen choice is influenced by what kind of paper you are writing on. For writing on scraps of regular sticky notes or printer paper, it matters a bit less. Tomoe River Paper is a bit unique, and the Jetstream pen that comes with Hobonichi Techo is perfect for this purpose. I really wanted to use my Kaweco Sport (a fountain pen) -- which I love, undoubtedly -- but the ink takes too long to dry and easily smears, especially since I am left handed. Some people do manage to use fountain pens on Tomoe River Paper, but have to use ink blotters or products that dilute the ink. I haven't found an ink blotter I love yet, so I haven't gotten one, though I'd love to. The Kaweco Sport is small and I feel comfortable bringing it with me on travels. I just wish I'd known there was a sample pack of the different ink colors before I committed to buying a whole pack of blue cartridges. I have two dip pens for writing -- one glass, one more traditional -- and I would like to use those soon. I have some inks I'd love to try.
Pencils
Ironically, I find these mechanical pencils the best for both drawing and writing:
The eraser isn't the best, so it's still good to have a Mono eraser on hand if you're drawing.
I also like the Metacil metal pencil. For pencil hardnesses I prefer 2B to 2H ranges.
Notebooks and planners
I am a huge fan of the Hobonichi Techo. The Jibun Techo seems nice, but it's actually so detailed that I think it'd put my OCD into overdrive. I personally like that Hobonichis come in Japanese or English, and have little daily quotes. I don't write in it consistently due to depression (yay), but in a way that does show how I'm doing. When I feel a bit better, I go through my texts and photos and fill in previous days.
Stickers
I have too many stickers at the current time, but I like Midori. Washi stickers in general are nice, since you can write/draw on top of them.
Stamps
I have many stamps as well. The most practical ones have Frixion eraser technology and so can be erased, and are put on my monthly view. I also have some artist-designed stamps from a stationery event I attended in Ginza.