untailed means there is no connector.
tailed means there is one, but who knows what kind of connector that is =P
it's not always wise to go by manufacturer. each make sooooooooooo many fans with sooooooo many different specifications (rotational speed, size, power requirements, noise level, not to mention the various competing bearing types...)...
but panaflo makes nice fans, according to popular opinion.
as long as fans meet your specifications, get it.