Top 10 lists are a good way to get attention and traffic to a blog post. And the same can be said about top 5, 25 or top 50 lists. But could you be doing more to get search traffic on these lists?
Using Google Trends, a search for "top 10" and "top ten" yields expected results. "Top 10" is searched more, and shows up more in news mentions. So it makes sense to title your posts with the number rather than spelling out "ten." But when you do the same trends search for "top 5" and "top five," the results are different. It appears that "top 5" is searched more by users, but "top five" gets more results for news mentions. This is a question of style. The standard AP style dictates that numbers zero through nine are to be spelled out, and 10 and above to be written numerically. Therefore, it's no surprise that "top five" is found more in news results than "top 5." But if more users are searching "top 5" you could be better off putting the digit in your permalinks and tags, if not the title of your post. Now, Google is pretty savvy when indexing these differences in styles, so it may not make a huge impact here. But for other search engines (and vertical search, even bookmarking and social sites) this could make a significant difference.
Along this same thread, other usage differences could also come into play. For example, "7 Deadly Sins" vs. "Seven Deadly Sins," "eighth grade" vs. "8th grade," or even hyphenated terms vs. non-hyphenated terms.