[LONG POST - 4 months of trying different planners)
I always wanted to use one but I never thought of analog (paper) planners and tried a lot of digital ones - link to a post.
About 4 months ago I saw my friend at school using a pocket diary - similar to this image, he was writing down his tasks on it (he didn't use it again). That day I bought a good pocket diary of around 200 pages, till date I've not used more than 10 pages and its still lying around.
I realised that I was not going to use it because it was very thick and I couldn't carry it in my pocket. I bought this pocket diary. This was thin and simple, perfect for me. I've used it the longest before switching.
Initially I used to dump all the tasks and cross it after completion, later I introduced a date system and it was one date for one page. I wrote down tasks for the day and crossed after completion if something was incomplete I migrated it to next day. This worked well but I needed a place to dump tasks that I had to do in future so I made a future section from backside and added tasks to it. This was the final tweak and I used it for like a month. I used it for daily tasks, future tasks, some notes and contacts (I used to make contact.txt before this).
Later IIRC I wanted to change because it was already half full and a mess because I was trying to do a lot with it. Next I mindlessly bought a notebook - something like this but with 5 sections, I didn't know what to do with it. I also don't remember why I bought it so I used it to write down stuff that I learned online and wanted to remember. It replaced my reddit save and I wrote what I wanted to remember, it is still with me and has been changed a lot (usecase).
I made a calendar on a single page of that notebook and tracked down basic stuff on it, I started using small square sticky notes to write down tasks and that's how I left my pocket diary. Not long after I lost interest in that notebook thing and updating calendar daily was not interesting. I left that and searched a lot online. Again tried a lot of digital options but I know it will never work for me so I left it and didn't use anything for like a day before I stumbled across Strikethru.
I took that notebook and turned it into a bullet journal, I used it for ~a week before trying strikethru and then again switching to bullet journal after a week. That was testing period and I chosed bulletjournal (bujo) over strikethru. That book was also thick so not long after I made a new bujo notebook (normal 200 pages). Again it felt like a big task that I had to do daily and I lost interest, I again restarted it with a new design. In this month I switched to different notebooks/design a lot and was never satisfied. I also tried Nextcloud tasks for 3 days before again trying out bujo.
Last year in december around a week before christmas I wanted to change it all so I went to a store and bought a new grid notebook (we used it for doing math in 1st grade). I used it for 10 days and everything broke during the last week of december, I was not at home and we went on a vacation. I took it with me but didn't update it because it was boring. It has been 5 days I was busy organising everything else again and now I've settled on what I started with (slightly better idea).
During that time I read a lot on nosurf, pornfree, internet addiction, sleep cycles, polyphasic society, tulpas, made new friends, tried a lot of todo managers, used different journaling apps and this is what I've decided to stay with.
I went to the store today to buy the same pocket diary that I've used the longest (1 month one). Its cheap, for 15 INR and works well for me. Over there I saw a box that said monthly planner, I took it and it had 13 small pocket diaries (similar to what I've used the longest but more thin) and with that a small case that would hold a notebook. There was one contacts pocket diary (perfect) and 12 pocket diaries one for each month. It was for this year and costed 170 INR, I didn't had money so I asked the storeman (idk what we call them, here we call them uncle) did he have cheaper option. He showed me the same piece that costed 140 INR but was for 2016, he said he would give it to me for 70 INR because he would have to throw it anyways.
I thought that was a great deal and bought it. So now I have 12 mini diaries for each month and one contacts diary that has my big list of 10 friends contacts. After trying a lot of different options I came back to what I used for the first time. Its simple and stupid & fits in my pocket.
It has one page for one day and I just have to cross 2016 and the day (mon, tue, etc.) thing and update it with 2019 days. In the middle it has a big two page calendar for current month, page before it has previous months small one page date list to write down events and on page after it has next months small one page date list. The last page is for notes and the cover has 2017 calender that I won't use and ignore.
Theres little patch work todo but for that price I think I bought a good set and if I actually use this for full year then I would buy a new one next one (for 2020 & not 2017 :|)
I've spent around 300 INR for all these (~ 4.5 USD)
Tl;dr -> Used a lot of systems and in the end switched to what I used for the first time which is simple and fits in my pocket.