I went from the standard multi-client setup to GAIM. I stopped using GAIM because the Windows port is quite buggy when it comes to the GUI library. I remember accidently resizing a window would cause GAIM to enter an infinite loop. After getting tired of this, I uninstalled it and looked for a new client... but I also needed one that supported the features that I've come to enjoy.
I tried Miranda, but it wasn't enough. It was too basic (as odd as that sounds).
I tried Trillian (and I had tried it before GAIM as well), and it was hard to get used to as it was a bit quirky, but after a good week or two, I was able to get used to it. It offered what I wanted such as logging with showing user history in a newly opened chat window. Unfortunately, I don't care for its way of organizing chat windows. I ended up having to set them to a single container with a blank name.
I'd say, if you just want a simple client, go with Miranda. There are plugins, but I try to avoid that hassle at times. If you want something that's fairly feature-rich, I'd say to look up Trillian.