I normally would say WinMX as I've been using it for ages but now that isn't the case.
I used to use WinMX for all my music download needs along with another program called NapMX. I used to dl a bunch of servers that were updated all day every day & then save that list & add it to WinMX.
When I did this, I would have the WinMX main server as well as a boatload of others to find stuff. NapMX for some reason no longer works as of a few weeks ago & the results showed when I searched for files on WinMX as I hardly would get any hits.
I have tried this program called SoulSeek which is more for underground music & it has been working well for me. You might want to give it a try.