I am subscribed to streaming services. Just want offline files in slightly higher quality. I find 768kbps+ to be perfect on high end gear. Streaming is great for 320kbps equivalent.

It doesn't matter on the go because even a slight outside noise would mask any kind of pseudo or real gains in sound quality.

I would recommend this website: https://free-mp3-download.net/ which is also listed in the megathread.
It takes music from Deezer in HIFI quality (FLAC 16/44). You can either download it as FLAC (lossless, but also large), MP3 320K or MP3 128K. Even the same bitrate will give you better quality since you're not re-encoding from lossy source.
From my experience, it doesn't accept characters like apostrophes in the search box. Hyphens are fine.

Spotify has basically nothing I've ever tried to actively listen to. It's also missing tracks of larger artists. It's also still subject to licensing which means what you have saved isn't guaranteed to be there forever (unless you're using a spotify downloader, I guess. I don't know why you would if you feel comfortable enough paying for it but not enough that you won't still download them?). Personally, to me it seems crazy to pay $10 a month for music I'm probably going to listen to for each month for the rest of my life? People always say it's great for discovery but I don't see how it's any better than any other avenue of finding new artists and releases. The convenience of an online app isn't very convenient for me, it being streamed is something that affects me on road trips and I'd need to have the foresight to download something, vs permanently having the songs on my phone (or a step further, microSD cards filled with music.) Like it was before? Just like Google Photos, if I can host my own photo backup on my computer why am I paying someone else an exorbitant fee? I can take this even further, I have Plex setup (and other music servers) and use Plexamp which is essentially my curated Spotify. Bonus: I have my core music on my phone, I have extra music streaming to me.

It also doesn't seem to be sustainable, each yeah Spotify operates at a loss while artists get very little payout from it. More than if you pirated from them, sure, but much less than if you just buy the album directly from their options be it physical or digital, or buy just one concert ticket and one merch item.

All this said, as with most things these are subjective case by case freedoms. Many get what they need from it and that's good enough and they're happy. Others just like to rip it all themselves and setup bubbleuPnP servers, and some probably are still just only playing CD's through their car that doesn't have AUX or bluetooth. If your decision to listen to an artist with the intent to give them your money, you probably should buy things from them instead of listening to them exclusively on Spotify you pay for. If your decision to listen to music is to just hear stuff, discovery, and it has even just 60% of a catalog of songs you'd listen to, the convenience is probably worth paying for. Especially given that technically the alternatives I've mentioned have an upfront cost of a computer and hard drives - for what it's worth only the cost of 2 years of Spotify and ~2 to 4 hours of setup time, but still a larger cost nonetheless.

That's worth it for some, they just prefer having it all physical/digitally stored and accessible for sampling and playback, the discovery and library probably aren't as deep as what they're looking for.