For me, I use 3-ring only because it offers me the best flexibility. I don't scrapbook chronologically. I scrap what inspires me so a 3-ring allows me the freedom to put my albums in chronological order after the fact. Hope this gives you some insight. I'm sure others will chime in too!
I started out using post bound, because the K & Co. post bound albums are so pretty. Now I exclusively use 3-ring. You can have a larger number of finished pages in the 3-ring, and they just feel nicer in general. You can get extenders for the post bound albums, but you can't use many or they aren't very stable.
The transitions from a post bound or strap hinge is hard, because 3 rings are Just bigger with more space in between pages. I moved from strap hinged albums that were smaller and fit on shelf easier, however once I started to using binders I never looked back. I found adding and moving pages so easy but also I had options for different page configurations. Mine even allow me to use 8.5 x 11 protectors to add interest or smaller memorabilia. I also like that if I make a thicker page or a lot of pages for an event my book wasn't bulging.
Again it's not as "compact" as the other styles but I think you will find over time that the positives will out weigh the negatives.
Another 3 ringer here and for many of the same reasons as others have mentioned. What turned me off years ago on post/hinge albums was; I ended up with too many albums that were not true 12x12 (years ago) and I either had to cut my pages down, usually after they were completed, or have the page protector ripple and wave with a slightly too big layout!!! It was too frustrating, especially when I learned I do not like scrapping chronologically anyway!!!
Having that larger gap between pages never bothered me, I scrap more companion pages than pages that extend from one side to the other! Recently I have been doing more double pages where the design flows from one page to the next!!?? Go figure!
One thing about this art, you don't have to scrap the same style year after year......
I was a post album scrapper. I finally got to nearly 30 albums and they stuck out too wide on the bookcase - the edge you open was so much wider than the spines that they looked stupid on the bookshelves. Plus, I couldn't mark them on the outside spine so I spent hours sometimes trying to find one layout which I also hated.
Went to 3-ring for about 4 or 5 years. I was never happy with the 3-ring but thought they would grow on me. I liked getting more pages in and I liked being able to move things around easily. I liked the slot on the spine where I could list what was in it. Still, they did not grow on me and I liked them less and less.
Last year I pulled out my old post albums and put all the pages back in them back only I put less pages per book so the open-edges aren't wider than the spines.
I have always steered away from 3-ring because of my experience with them at school - I always seemed to end up with the rings getting bent and not meeting properly, which can wreck pages when they get caught.
I also find them cumbersome and never feel they are quite as safe as a post bound. Dropping a 3-ring can be disastrous.
They may have improved since school, would like to know what others think.
I use both. I used post albums for my kids' 1st yr - my absolute favorite pics and pics of each kid w/ special family members or special events. I use 3 ring albums for the years after. The only thing I don't like about 3 ring are that I have to go through and replace page protectors that look torn or pulled. My kids (9 and 3) love to look at their books, they're just not as careful w/ the pages as I am.
Post albums are great for showcasing a vacation, special events or as a gift album.