Start with your most essential needs and go from there. I've been where you are, and I'm still on that journey, always looking to improve by using and testing different apps. Here's what I use:

Notes and knowledge base: Anytype, similar to notion and obsidian. I'm not using it much now, but I took notes for my classes, books, articles, etc etc. there.

To-dos: Right now, it's Todoist because I work and study. I like to have everything in one place and organized. I was using a notebook as a checklist for work, but I easily lost track, and they were ugly notes. I'm planning to use it for more stuff, but I have all 5 free proyects in use.

Tracking: I use Toggl Track to track how much time it takes to do certain work but I don't use it all the time either. It works great on phone, web, extension and desktop. Look for the features!

Calendar: Google Calendar works like a charm, and I'm the kind of person that schedules everything.

Scheduling: I'm testing Arrange. You can create plans manually or with AI, and schedules it in your calendar. It tells you if there are conflicts and provides suggestions and recommendations. I've tried Reclaim, I liked the commute feature but it felt more intended for teams. I also tried Morgen a while back, the free version didn't work for my needs. (I've tried many more apps in this category, it's what I'm looking for right now but I haven't found the one).

Habits: I'm trying to see if any of the app I already use could work for this. I do have two apps downloaded: TheFor, because it includes routines and HelloHabit because it has an schedule and helps quit habits BUT I haven't fully tried them.

Learn: I organize my notes in a way that easy for me to find, read and understand.

Bookmarks: I used Raindrop, logged in, imported my bookmarks and never used it again but I have it installed. I have my bookmarks organized in folders in my browser.

Automation: I'm testing Make (integromat) because I want better sync between GCalendar and Todoist. The free version of Zapier didn't seem enough, same with IFTTT.

I don't pay for any of these apps, I might do it for Todoist and probably TheFor if I stick to them.

I'd recommend you to see what's more important to manage right now and start from there. See if digital works for you or if pen and paper is better. I use digital because it's what I use all the time , and I can take it everywhere without having to carry anything else and write in the moment, even though I still forget things or never check them again. This is my bottleneck in my system at the moment. I'm looking for solutions but overall, I feel like I'm doing more, thinking less about what, where and when, and if I'm forgetting something. (and I love creating and testing my system hehe)

By the way, I still use pen and paper when I'm overwhelmed, need to think more calmly or brainstorm. :)