With my diary I'm always torn between writing out all my thoughts and feelings or simply saying "today I did this and this".
I think I find it rather hard to talk about my feelings.
I tend to do both. I've been writing diaries on and off since I was 16 or so, more consistently since 2018 and more or less daily since mid 2021. A typical entry will be, in this order, 1) anything interesting that happened at work, if I've been busy, any drama, etc 2) any other stuff about my life, feelings, dreams I've had, gossip from my mum about the village she lives in, etc 3) a short precis of any news stories I'm interested in.
I've always said that I do - at some point - want my diaries to be published, so meh if people read them and I've posted my entry for the day Prince Phillip died on Twitter. Partly because of this I obfuscate people's names if they aren't famous (although I do have a list on my computer, and I'm not always consistent about the abbreviations I use). I alos don't quote song lyrics except as tributes to be people who've died.
Notepad wise, I'm currently using some of the Tesco A4 journals with 192 pages that are about £7 each. The previous one lasted me a little over a year.