What is best for seo sub-domains or new domains

Hey guys i am building a site and currently cant decide how to over come this problem

The site is split into 3 main sections of services they provide

would it best to create 3 subdomains or

three different domains

which of these would be best for seo purposes

cheers Andy

 

Any reasons behind ruling out different folders?

 

Three different domains if you use service name in main domain. If you use company name in main domain then three sub domains.

 

I would be using a main company name

my thinking behind 3 different domains is for site submitting so i could submit 3 sites