When, at the University of Warwick, I began my academic life back in 1997, I was astonished at how bad reference management software was.
Pretty much everyone recommended using EndNote. But I soon learnt that this wasn't because they liked it. It was because everyone else used it so if you wanted help or to share reference files, EndNote was your best option.
But, in this writer's humble opinion, EndNote's interface is an unequivocal disaster. The software is also slow and just feels heavy on your computer. It's expensive but at least they do Windows and Mac versions.
I was pretty distraught each time I had to do some serious referencing until, somehow, I came across BookEnds four years ago. BookEnds works how I expect referencing software to work. It's easy to use, flexible and powerful… it's fast and affordable. The developer is friendly and responsive and new versions are regularly released. In other words, joy of joys, I can enjoy referencing again.