I remember why I switched to Google: 1. speed, 2. simplicity. Relevance, meh. Never noticed much difference there. This led me to believe that PageRank was more about marketing (brilliant marketing) than technical edge.
Are you kidding? I was using Altavista, IIRC, and would routinely have to page down to the second or third page to find any kind of relevant link. When I switched to Google, I almost immediately stopped looking at more than the first page of results.
There was nothing wrong with Altavista's algorithm for "finding stuff" - it was just too vulnerable to SEO pollution. I remember the quality of it declining almost overnight once spammers (yes that's what SEOs are) figured it out.
PageRank was of paramount importance back then. At the time, AltaVista/Inktomi were easy to spam, and Google wasn't.
The google spam that actually works (or at least, worked a few years ago, before panda) requires setting up lots of sites, lots of independent IP blocks. That was much harder when PageRank appeared - hosting was damn expensive, VPSes were nowhere to be found.
PageRank was a huge thing. I used "and" queries in altavista at the time. It was no match.
Initially the no. 1 reason for me was peer pressure. It was simply unacceptable to use something other than Google in tech circles at some point. It was like having an @aol.com email address.
If your users are that passionate, you're doing something right.
After I gave it a go for a while, the other reasons you list made me stay.
This is purely subjective, but Google is the only one that links to the Netlib 'real' LAPACK, straight to the file/documentation in question. The others have mixtures of Java packages and other examples...
Basically, but you're getting the opinion of a random person on the internet :). The third result is the 'real' one (the top two are unit tests for the named function.