My jean size is also 25/26. Like you, I want my belt to have total flexibility. I have 78, 80, and 85.
The 78 with a few holes added is only good for high and natural waist.
The 85 is best for low waist. i had lots of holes added so I can wear it on my true waist too, but there is excess material to curl around. It doesn't show, but it does "thicken" the waist a tiny bit visually.
I recently bought an 80 in a different width, with the idea to use it for all positions. With holes added, I find that I can wear it in my jeans' loops but it is a tiny bit short. I can also on my true waist with a dress. There is still some excess material though not as much as the 85.
Having tried them all, I think the 80 is OK if you want to have just one belt for all positions, but if your jeans are really low-waisted, you might wish for a tiny bit more length and go for the 85. If you wear it on your true waist a lot, the extra length in the 85 might bother you if you don't like to have that extra bit to loop around.
I really like having both the 78 and 85 in two belts of the same width. I bought them in different colors, with one gold buckle and one silver buckle. I was totally covered for all possibilities.
My 80 is a different width and I don't want to buy another belt/buckle, so I like having one belt to do it all.