My advice would be to take a couple days and really think about how you use (or intend to use) your iPad. And I strongly suggest you go to an Apple Store and check them out for yourself. Work with them, handle them, etc. to find out which is better for you and your uses.
I was in the same situation as you when I was considering upgrading my iPad Pro 9.7 – should I get the 11 or 12.9 iPad Pro? I really wanted the 12.9 since the physical dimensions were smaller that the previous generation, but the screen was still large to work on. On the other hand, the screen on the new 11 was bigger than my 9.7.
After playing with both in the store (and walking in with an 80% intention to get the 12.9), I got the 11 inch. Why? Weight. Yeah, the 12.9 screen is great and works with two fullsized apps when in split screen mode. However, when outfitted with a smart folio cover or keyboard folio cover, the 12.9 was significantly heavier than the comparably outfitted 11 inch. That mattered to me bigly since my iPad is effectively a laptop replacement that I carry in my briefcase for work every day.
So again, check out both models in person. Don’t rely only on specs you see on the internet. It’s important to handle these devices before you buy because it may change your perspective. It changed mine.