I find the Kikin and Opera Mini browsers to be pretty decent (on iOS 4.3.3). I use Kikin more than Opera Mini, since it's easier to switch between tabs. And I have no problem viewing the default forum skin with either of them.
Opera mini being one of the few (maybe only) actual alternative browsers on iOS, all the others are mostly just new UIs for Mobile Safari's rendering and javascript engine (since Apple seriously limits what a program can do on iOS, which is the reason why Mobile Firefox will never be released for iOS, as you are forced to use the javascript engine even if you do make your own rendering engine work on iOS). Opera mini gets around this by downloading prerendered pages from Opera's servers, and is also why Opera mobile will never be released on iOS. Dunno anything about Kikin.
Also, default skin is a tricky question. Do you mean the default desktop skin? The mobile skin? Which one is the OP using? Hence why I suggested trying a different skin to resolve the issue.