KatFile will be Discontinued... one day
UPD: so after reading all the comments and reviewing the rating, i've decided not to replace KF until there will be a really decent alternative, because the only one i had in mind is NitroFlare, which is not that much better than KF, but at least they are one of the strongest on the market.
Remember, to me the top criteria is reliability, which means that FS has to be around for at least several years and developed good reputation;
it also has to be widely used elsewhere, so you wouldn't have to buy premium just for AudioZ.
most of the alternatives that you mentioned are either new, have bad reputation, don't work somewhere or for someone.
Torrents are off the table. It was almost perfect file sharing protocol, but these days they are so massively blocked and even prosecuted in some countries, that i simply don't see any future for torrents on this layer of internet.
I had high hopes for iPFS since they started and i keep watching it, but even so far iPFS doesn't work as it supposed to.
therefore let's leave things as they are for now, but please don't pay for the annual premium expecting it to last in this unstable industry.