Currently, there are only two ways that channels (aka buttons in the Tools --> Options --> Display). Those ways are either by the time you joined the channel or, if you check "sort buttons", A-Z.
As someone who "idles" channels a lot, and has a different set of channels that are more important than others, I'd like to be able to click and drag channels in the list to the positions I want them.
This may be asking too much, but I'd also like to be able to "join" multiple servers that I'm connected to together and be able to sort within those, as well. So, if I'm on three networks, and one channel of each of those is the most important, I can move each channel from each network to the very top and they're all together to make it easier to navigate between channels.
The second suggestion I have is regarding the "Next". Currently, Ctrl+F6 is to go Next and I have yet to figure out what determines which channel it goes Next to. I have a feeling it does it by last activity in the channel, but I'd like the option, at least, to be able to go Up and Down rather than Next by activity. So if, say, my channels are ordered: #A #B #C, if I'm on Channel #B and I go Down, then I go to channel #C, regardless of whether that channel had the latest activity.