choosing domain names

hey guys.
i have brought a few websites here, havent recieved them but obviously got the domain names
what domains have been sorted are bestof,,,

now are these how most micro niche website names are developed by having the actual keyword as the title ?

does it give it that much oompph or something.

if the keyword is searched would that come up 1st??

Would you always be competing with the big boys if their pages come out like yahoo.com/bestof....