Alright, so I've been messing about with mobile piracy for a few years, so I've got a decent knowledge on most apps and stores used, and I haven't seen a large thread on this topic recently, so I figured I'd make my own to document the apps so far that have proven useful for me and hopefully for you guys too.

Now, mobile piracy is easy. Ridiculously so, at least for Android, but like I said, this is for beginners.

As a disclaimer, I'm going to assume your phone has its bootloader unlocked, and you have TWRP Recovery flashed so you can flash Magisk. Those are two guides that can vary greatly depending on your phone and model, so I won't get into them here, however they're fairly simple if you can find a guide over on XDA-Developers. I'm also going to assume that you have a decent knowledge on how to use a file explorer that isn't the stock one (Solid Explorer/ES File Explorer), and how to set basic settings.

As a starting point, make your phone has the setting "Allow installation from unknown sources enabled", this allows you to install apps that aren't downloaded through the Play Store. You can find it in the Security menu.

Now we'll go over some useful apps that aren't stores, as stores rightfully deserve their own section. There aren't many I can recommend here besides Freedom as Lucky Patcher died with XPosed, and the other apps don't work as good as Freedom does.
Magisk - The only root tool you'll need. It's systemless, so you don't need to reflash between updates, and it works on every Android device out. It also comes with a SafetyNet spoofer, which stops Google finding out you have root while an app launches, such as in Pokemon GO, and locking you out of it. There will be downtimes however as Google and topjohnwu are in a constant arms race. It also contains a bunch of modules to tweak your phone.

[Freedom](freedomapk.org/blog/) - Freedom is almost essential for certain apps that allow free downloads from the Play Store, but contain in-app-purchase blocks, along with offline apps that have in-app-purchases anyways. The only series I can think of that uses the former model is Hosted/Choice of Games, but Freedom works perfectly where other apps that manage in-app-purchases fail. To run Freedom, just install the .apk file, and enable it in the top menu. Contrary to belief, you do not need to run the app inside Freedom for it to work. You can launch it from your app drawer, which is faster. You can check if Freedom is running by attempting to purchase an item. Freedom is working if the card you're using appears as** FreeCard XxXx**X instead of your usual method. If a game doesn't work with Freedom as it's online, it will simply say the transaction failed, and you can go back to playing. You'll also need to make sure your Play Store is version 7.8.40, by uninstalling it, and placing the correct version in your /system/priv-app/ folder.

Titanium Backup + Pro Key - This is the only app I can say is the best app you will ever spend money on. Functions perfectly and quickly in backing up apps. But you're probably wondering why you'd want one. Well if you want an app quick and you can't find it in the below stores, you can simply buy it in the Play Store, back it up with TB, and then refund it. Incredibly simple, incredibly easy. Provided you have the money and are able to access it of course.

And here we get into stores. Now there are two stores to speak about - ACMarket, and Aptoide.

ACMarket - I'm not entirely sure how ACMarket produces its apps, however I believe it's curated by its own team, as there are no 'user submitted' areas I can see. ACMarket is great for paid mainstream games. The UI is stellar, and downloads are decent, if a little slow. You should be wary that a small number of apps are also packaged pre-hacked with the usual 'unlimited cash' or 'infinite XP' stuff you see, if you're not into that kind of stuff and just want the game in a normal state like me. You're also less likely to find much other than big-name apps than Aptoide, which is why we're using both.

Aptoide - Aptoide is functionally infuriating, yet genius. It acts as more of a map to various stores than a store itself in that it hosts user-curated repositories of games. This means it will most likely never be taken down, unless the developers decide to discontinue it. This is also means that you're likely to find older versions of apps if they've been recently updated, and the search is a little wonky. However, it's surprisingly good for the more niche apps that ACMarket doesn't have. Some good repositories for Aptoide include nitrogamer4k, sandro797, and pubnativestore.

credit goes to reddit: u/Rush_B_Blyat

As from myself, i could add:

Mobilism is incredibly good place with whole variety of apps and games, and books as well

Just one more tip, always scan everything downloaded with Virustotal.com, and try to download only from verified and respected uploaders, to minimize the chance of downloading any form of virus.