I hate S2. Too many of the styles have nowhere near enough customisability. My existing journal layout is a horrible kludge in S1 which mixes together bits of Generator and bits of Classic to create something I like: specifically, full-width entry header bars on all pages and full-length entry sidebars in my friends' colours on my friends page. It could not be less compliant HTML if it tried, which is the reason I'm trying to replace it.
I know this sounds somewhat anal, but the reason I like these bars around the place is that they let me browse lj (specifically my friends page) without having to read every single part of every entry. I often skip posts when I'm in a hurry, and I've found that pretty much all the default styles add too much time to my lj viewing experience (as I'm left looking all over the entry to find out who wrote it, or having to scroll erratically to try to find the end of it). Also, I get headaches from computer use even using the LCD screen on our laptop with a very small font size - so I want to try to minimise eyestrain. The problem I'm having is that S2 styles are easier to customise than S1 was - but they do this at the expense of flexibility.
Basically, I don't actually like the look of that many of the S2 styles. I've always hated Clean and Simple, Notepad and Punquin Elegant. I really really hate Tabular Indent (I think it's all those "View:" lines in the header box). Many of the styles insist on using a default text size that is far too big for my eyes, or serif fonts, which hurt my eyes in any size. Styles with sidebars like Component or Digital Multiplex are uncomfortable. So this really cuts my options down. I liked Haven (you can move the sidebar to the right, where it bothers me less), but it's not customisable enough. Meanwhile The Boxer looks fantastic, but the headers at the top eat up 2/3 of my 800 x 600 screen!
All things considered I think the only choice left is Unearthed, but it has two very annoying "features" by default: 1) if you turn off userpics on your own journal page, it removes them from your friends page as well (!), 2) it does not make any use whatsoever of friends' colours. So it looks like I'll pretty much have to write my own custom style - which is what I was trying to avoid. I don't know anything about stylesheets, and I don't really want to learn (the reason I like lj in the first place is that it lets me publish my rambles on the web without having to lay everything up in HTML each time!). But I'm not sure I have any choice.
Unless anyone who's an S2 wiz would like to code me a layout for money? (serious offer!) ;)