Lander 90% of the time. Most offer pages don't have what it takes to muster the conversions.
Typically I revert to the basics of selling. As you may or may not know people buy on emotion and justify with facts. With that said if the lander doesn't really stoke that emotion and get them hot and horny for whatever you product is. Then I have to do a presell. Almost always offer pages are forms + facts.
Lets take a couple examples. First a diet lander is typically just a bunch of news sources, maybe some celeb pics and a couple hot buttons bullet points. But really nothing to get those emotional must have juices going.
Secondly we'll look at dating. Dating can work direct sometimes because the whole idea is "I want to date a hot chick, oh there's a hot chick on this page, it's free I'll signup." A mere picture of a hot chick and that's what they want is usually enough to get those juices flowing.
Hope that gives you some insight into my decision process.
As always just my 3 cents.
