If your site is a MFA I would imagine ads at the top. If however you have a quality site then the ads are better at the bottom - afterall if you have a quality site you want your visitors to read or purchase your product/service not exit to another site. Numerous threads site that typical MFA sites have ads at the top - and these seem to be frowned upon. I think Adsense may take ad placement re MFA sites into account in the future. IMHO :)

I would ignore that (with all due respect)
and do some reading here
[google.com...]
specially here
[google.com...]

I'd suggest trying it and finding out - all sites have different results with placement and you need to find out what works best for your site. Trial and error is the only method I'm afraid.

If you are an MFA is doesn't matter.

ou have Ads instead of the content - then add some more at the top and the bottom!

:-)