I mostly use RUTracker and TParser for torrenting. Sometimes I find torrents, ZIP's, links, etc. on other sites but those two seem to give me the best results because they usually have what I'm looking for. TPB is alright but I haven't had much luck there with some stuff recently. Iirc, I used KAT a couple times before it got fucked to hell and back. Can't quite remember what my experience with it was like.
As a general rule, I only buy shit when I can't find it for free anywhere in a direct FLAC rip, a 256/320 kbps AAC iTunes release or, at the very least, 320 kbps MP3. Bandcamp and iTunes are really the only digital stores I buy music from, the latter only if it's either an exclusive or I can't find it anywhere else. Sometimes I buy physical CD's, usually of obscure OST's that lossless or even halfway decent rips are nearly impossible to find or out-of-print releases from artists that are reasonably priced and I impulsively buy every once in a while out of fear that someone else will do it before me and my only choice will be to buy it from some flipper asshole selling it for $30+ more (that's actually happened to me before). Vinyl's too goddamn expensive for me and I don't even have a record player to begin with, but there are a handful of releases/versions of releases I really want that were only ever issued on vinyl and that I'd love nothing more than to rip directly to WAV's and add to my digital collection.
However, while it does feel good to directly support artists through sites like Bandcamp, it pisses me off and deters me from buying an album when only two out of the 5+ tracks in the release are stream-able as per the artist's choice and they still expect me to pay a whole fucking $5 for it with just a large JPG or PNG of the cover art as the only other thing included, which is actually standard with pretty much all releases since you have to include that if you buy the whole thing. This has happened to me several times as of late and it seems to be an unfortunate trend.