Well, that's not a wise vote. They use flash for testing. Flash is the worst protocol for internet speed testing. Ookla admits in their own wiki that they adjust results up to 30% for an unknown variable
. (read http://wiki.ookla.com/test_flow).
TestMy.net on the other hand doesn't rely on any 3rd party software and is not adjusted at all.
TestMy.net has also been testing connections for nearly a decade longer than speedtest.net... that's more proven if you ask me. The majority of people use speedtest.net because it's pretty and cool looking... the majority of people also don't know anything. If you want accuracy then I've told you were to look already.
Up to you... go where everyone gets lied to or go where the experts go.