My understanding is that IQ tests measure some dimensions of intelligence, but not others. That matches my experience.
Back when I was a kid I was administered an IQ test. I scored in the upper percentile, I’ve always been pretty good at reasoning, pattern recognition, and creativity. Those were qualities that the test I took measured, but I struggled (at least relatively speaking) with social, situational, and spatial awareness.
I think determination would be another trait wasn’t being tested for, but that’s important for hitting targets in a large search space. It’s quite likely that things have changed. It’s been 40 years now.
I’m use Notability, but mostly because I prefer to use hand-written notes. What I like is that I can hand write my notes, and then be able to do a text search on them later.
It started with me taking notes while playing RPGs, but turned into a daily journal.
If you don’t care about handwriting, my only real suggestion is go with something that saves files in Markdown format. If the company goes poof some years down the road you want to be able to still access your notes.