The Voth have superior Transwarp Drive to the Borg. The Borg need Conduit networks, the Voth don't.
The Borg don't need
to use a network, they choose to. Or at least, that would seem to be the case considering the use of transwarp in Descent
I think that method of transwarp is slower, at least from what I can gather
the Voth seem to be able to cover tens of thousands of light years in very little time at all, whereas i think that still takes the borg months of time without use of a conduit
could be wrong though