Interesting. I use a RedHat 6 derivative and I don't remember the last time I had a real crash of app or OS (save for trying to install RH7, until I figured out that it -- probably kernel 3.x actually -- won't boot with AMD cool-n-quiet enabled). But then, I don't use javascript/flash/etc, I don't let applications self update, etc.
I've actually been thinking about looking at Ubuntu for the LTS (Long Term Support) line, as a lot of folks are using it for openstack.
If you're seeing crashes, something's wrong. It doesn't need to be that way.
BTW, if by "scan documents" you mean using a scanner to save paper documents to pdf, et al, you might want to take a look at xsane it you haven't. I've never figured out how to scan multiple page documents with it, but then 99% of what I scan are single page anyway, so I've never put much effort into it either.
I never had crashes with earlier versions of Ubuntu. I started with, IIRC, Ubuntu 8...someone steered me over there. I'd tried RedHat around 2002, off a CD, and it didn't work hardly at all with the Wintel boxes of the time. I had three, two bought secondhand, out of an office-furniture liquidator's; and then an HP. Two old P2 boxes and one Pentium IV. Didn't work on any of them.
Already I was cloning my HD with Ghost, saving Windows 2000; so I could wipe the hard-drive and install RedHat. Dual Booting wasn't around then.
RedHat didn't recognize my modem and ran at an incredibly-slow pace. I don't know if that distro was supposed to be intentionally kludgy, as a teaching tool, for programmer wannabees to open it up and rewrite it...but it was unworkable. Later I'd see Red Hat for sale in CompUSA. Uh-uh, brother...
In that environment Ubuntu was a revelation. Went in easily and painlessly and WORKED. EVERY time.
Versions 8, and 9, didn't crash. Version 10 was the one they forced the patch to seal the flash-video backdoor...interestingly, I'd tried any number of ways to capture FLV vids and nothing worked, and then one day I was on a Ubuntu discussion board, and it was spelled right out there. I tried it immediately, and it worked just like the poster said.
Two months later I made the mistake of booting my machine while the Ethernet cable was plugged in and the modem on. Forced-update...and that was the end of my Yoob Toob video library. I did at least get the full World at War series...
Only starting with version 14, have I had frequent crashes. The more updated version, 16, it happens more frequently. I have the two side-by-side on this old Toshiba machine. Toshiba used to work flawlessly with Ubuntu, but maybe they're using different test mules now.