I would never use chop to remove newline characters, chomp is so much better for it. It can be a handy s/.$//s-shorthand, but you won't need that much :)
So all things considered, my answer would be: never. Never use chop instead of chomp.
Lbh ebgngrq guvf grkg naq abj lbh pna ernq vg. Fb jung? :) -- Whreq