Boot fit is incredibly important. Flex matters as well as fit, but a too-soft boot can't be made stiffer while a stiff boot can be made softer.
You're in a 25.5. That's not so difficult to find. In October-November all the shops will have your size in just about everything.
About that flex -- 80 flex in an adult boot is for beginners and cautious novices and lower intermediates. Such a soft boot will not support you at speed or in nasty chopped up snow that wants to throw you around. I was thankful for my stiff boots (110) this last week because the snow was soft and dense. If my cuffs had given way, I'd have gone over the handlebars. But I was traveling faster than most on that spring snow, aka that sticky slop. You might not want to ski that stuff.
The advantage of a beginner-soft boot is that the cuff absorbs a beginner's awkward movements instead of transferring those movements to the skis. The cuff flexes as you move into it, but nothing happens to the ski in response because the boot's pressure on the ski doesn't change. This can be beneficial when an advancing skier is making movements that are not so useful.
The stiffer the flex, the more precise the skier needs to be. If you are wanting to build precision movements and higher skills, a soft-flexing boot at 80 probably won't transfer your moves to the ski in a timely fashion. You won't know if those moves are working or not. You'll have to over-do the movements to get the boot to do its thing, and that takes up time within the turn ... thus my use of the word "timely." In other words, if the ski gets the message, that message gets to it slowly and its response is delayed.
Low flex boots for juniors are stiff to them since they are small people still and don't weigh much. They won't be flexing an 80 boot as easily as a full-sized adult. So an 80 junior boot is not necessarily a beginner boot for a kid-sized skier.
Also, the numbers denoting flex are different from manufacturer to manufacturer. You can't compare an 80 by Tecnica to a 90 by Atomic.
My suggestion is to go to a well-stocked store in October, one that carries as number of manufacturers. Call and make an appointment beforehand with their most educated and experienced bootfitter. Spend the extra money and get a good fit (length, width, height/volume) with a boot whose flex matches your ambitions, not your current skill level. You want that boot to last for a few years once you spend all that money on it. If it's a bit too stiff, you can have it temporarily softened by removing screws in the spine.