Adding Blog To Existing Site - Subdomain or Folder?

I have an existing domain that's static HTML.

I'm looking to add a WP blog to add future content, what do you guys think is the best format -

www.blog.mydomain.com

or

www.mydomain.com/blog

Is there any benefits either way or doesn't it really matter?

Thanks

 

Both work well. If you do it as a sub domain, thats kinda cool because its not done very often.

 

I thin this is better: www.mydomain.com/blog