I got my start in the RPG hobby with the AD&D 1e hardbacks. My first venture into the world of D&D Boxed Sets was a Moldvay Basic Set that I bought for $3 at a store that sold remainders and overstocks. I guess they were clearing out the old Basic for the new Basic.
The first "White Box" D&D like game was the Castles & Crusades White Box, followed a few years later by the S&W White Box (and later the D&D OCE White Box and Delving Deeper's White Box). The thing is, boxed game sets didn't excite me as a teen / young adult - they annoyed me.
They annoyed me because I was horrible at returning stuff to their proper box - I had (still have to some extent) "peanut butter in my chocolate" syndrome. I'd open up the boxed set for Birthright and find Runequest stuff.
Hardcovers and even most softcovers had the advantage of their title on the spine - I could pull something off my shelf and know exactly what I actually had.
As a middle aged 40-something adult, I appreciate boxed sets much more these days, as they look very nice displayed on a shelf, but for practical purposes I think I prefer hardcovers. They are just easier to use and reference in actual play.
How about you? Boxed sets? Hardcovers? Something else?