There are two contrary arguments for this:
Use what's most actively used. You can work that out with something like the Steam Hardware Survey (or wherever you can find that sort of breakdown). In this case it suggests the latest version is most popular but remember the biases. Steam survey statistics are gamers.
Use what's been around the longest. 12.04 was the latest release when it was first released and there has now been over a year of people bumping into problems, asking questions and having things fixed.
While you might find more people are currently using 13.10 (and might be more inclined to help you), you'll probably be more likely to be able to help yourself with an older release because the support already exists.
You're speaking as if a 13.10 user won't answer a question about 12.04 but you have to remember that even if the issue is very specific to 12.04, many 13.10 users used to be 12.04 users. Many (myself included) have installs of both. For the vast majority of problems, version means very little so I'd just go with whatever works best for you. It takes about 20 minutes to download and test Ubuntu so I'd spend a little bit of time working out what the best starting point is.
And remember that paid support is available for all supported versions from Canonical. If you're running into so many problems on a daily basis that it's made you make a software decision, you might need more help than the community can give you.