Does less have an equivalent to vim's scrolloff?

I believe you want the -j option. It doesn't seem to have a bottom-or-top mode, but rather a bottom-mode or top-mode. For instance:

less -j 4

Will always display your search term on the 4th line (from the top), whereas

less -j -4 

Will always display your search term on the 4th line from the bottom.

And of course, you can use alias to make your preference the default, by adding this to your .bashrc, for instance:

alias less="less -j 4"