I'll throw my opinion for Sync for Lemmy.

I have to admit I haven't been buying a lot of new apps the last few years. I don't play games on my phone and most of the apps I use daily are basically the same ones for a few years already.

• FX file explorer An excellent file manager that I have been using since forever. There are other good ones, such as Solid Explorer, but FX is my favorite.

• Tasker I used to play around with this so much, the things you can do with this app are endless. But I have been using it less lately, switched to Google home since it has better/easier integration with other devices in the house.

• Nova Launcher I think most of you will be familiar with this launcher. I have probably been using this one since it came out. It's perfect!

• JuiceSSH Pro To be honest I don't even know what features are unlocked by purchasing the pro edition without looking because it has been so long since I bought it. It's an SSH cliënt and one of my most-used apps.

• Sync for Lemmy There are plenty of Lemmy apps that are good but I was using Sync for Reddit since forever so I jumped on the hype-train when it came out. I paid for Ultra monthly because 2€ per month for something I use daily is a no-brainer.

Besides these there are some Google Wear watch faces I purchased. There had been other apps that I bought years ago like sdmaid or some other tools from when I used to install custom roms but I don't really use those anymore - too much hassle for marginal improvements. And the question was about apps that are still relevant.

Bitwarden

1. Mixplorer Silver - Feature-packed File Manager
2. Hermit - Lightweight PWA browser
3. Instaddr - creates disposable Email addresses
4. Readera - Feature-packed book reader
5. Moon+ Reader - Feature-packed book reader
6. Balance - for Meditation. They have been offering a one year free trial for some time now. It has been really helpful for me. Their programs are highly customised to achieve your goals. Give it a try.
7. KWGT & KWLP - if you're into home screen customisation, then these are must haves.
8. 1DM - Feature-packed Browser and Download Manager (Direct downloads & torrents)
9. Niagara Launcher - Lightweight, minimalist, with solid, fluid animations. One-hand friendly. Free version has ZERO ADS. I've been using the free version for a couple of years now. I'm hooked to it. I don't think I can go back to a normal App Drawer drawer style launcher now. They offer one time purchase as well for the pro version. I felt no need for the pro features, though i'd definitely buy the pro to support the dev.

Some of these have decent free alternatives. Mixplorer is free to use officially through XDA. KWGT & KWLP have free ad supported versions available through their official website. Regardless, these have been installed on all my phones for years now.

FairEmail : https://play.google.com/store/apps/details?id=eu.faircode.email

The best email app.

Business Calendar (by Appgenix Software)

I have multiple Google calendars to keep track of pretty much everything; birthdays, anniversaries, bills, when school is in session (I have kids), scheduled days off, various appointments, etc. I've been using this since 2011/2012 with their first version, and moved over to the 2nd version after that came out. It gives me more control over how my calendar looks on my phone, I can easily toggle calendars and tasks on or off...

Honestly, I can't use another calendar app now. I love my color coded (you can change calendar colors in the app to any color you want) month at a glance calendar.

And I also can't recommend KWGT enough for widget making. I originally got Zooper to try to emulate Conky (from Linux), but Zooper stopped being developed. I have a lot of fun trying to get my widgets just the way I like them - even if my code is a mess.

The only app I've paid for is Torque Pro. If you deal with cars a lot it's worth the 5 bucks. The free version is also pretty handy.

Niagara Launcher https://play.google.com/store/apps/details?id=bitpit.launcher

It's georgous and I've grown to love the list view for apps. As phones are really tall, it makes more sense to lay out apps vertically instead of horizontally. It's search function is great too.

My work uses google workspaces, the agenda widget is so useful for quickly seeing a list of calendar events and weather.

I don't have many paid apps, but one I do like is Peakfinder. It's not something I use all the time but it does become rather handy when you've climbed up a hill to a viewpoint and now want to figure out which other hills you're looking at.

For mobile- Poweramp - let's me view and play music by Folder. Google and Samsungs built in player suuuucks. You can't build a Playlist with Poweramp, but if you have lots of your "own music" .mp3s, I highly recommend it.

And SimpleGallery. Infinitely better than whatever the fuck "Google photos" puts together. It lets you sort and view by, you guessed it, FOLDER NAME rather than "most recent" always at the top. It also let's you Hide folders too for all those cute cat photos. Also allows Excluding folders, so that game thumbnail folder doesn't show up too.

For online and offline GPS I love OSMAnd+ since it has AndroidAuto support and tons of other features.

Solid Explorer

Titanium backup doesn't work anymore on latest version of android..

Last time I tried it, the restored applications would just crash, and the ones that did work don't have the external data backed up

Not FOSS but, I love TickTick, it’s a great cross-platform reminders app. I’ve tested a ton but TickTick is my fav

Sync for lemmy.

If you have root access, instead of Titanium, you can use instead oandbackup.

It's free and open-source.

KLWP and KWGT are amazing for customization. KLWP is for making live wallpapers, KWGT is for making your own widgets. They're both extremely powerful apps that allow you to completely customize phone home screen to your exact liking. There's a slight learning curve to them, but once you have the basics down you can do some pretty amazing things with them.

Add Tasker into the mix and you got a stew going!

• Automate. it's just 2 bucks.
• Sync for reddit was worth it, Sync for lemmy is absurdly expensive.
• HiPER calculator.
• FX file explorer (it's kinda dead though and doesn't work well with modern android)
• Kustom apps

I paid for Tilla, it's a great app to manage subscriptions. I get notifications when the next payment is due. Pretty simple UI but that's what I like about it. You can check how much you spend per week/month/year.

Slice & Dice is probably the best android phone game ever made, and if you buy the itch.io version you get both the PC and Android versions.

I am interpreting "worth paying" as "immensely useful" because I don't recall paying for an app, ever.

• Aurora Store: Basically Play Store but you don't need to sell your soul to Google. You can log in to Google account while staying signed out on Android or use "anonymous account" function.
• KDE Connect: File transfer, phone notifications on PC, stops video/audio on PC when you answer a call and many other features. Right clicking a file on my Linux PC and then clicking "Send to Phone via KDE Connect" is so satisfying.
• Samsung Notes: No non-sense PDF reader and annotator. It did not appear when I searched for Android PDF readers on the Internet and its name doesn't imply that function making it sort-of a hidden gem. Maybe there are better apps I couldn't find, though.

Moonreader - ebook reader

Onkyo HF Player - High Fidelity Music Player

CDisplayX - Comic Book Reader

Listen Audiobook Player

Niche but very valuable for me is: symfonium which is a very complete subsonic client. Prana Breath is a lean but featureful breathing app with a ton of different exercises from beginners to advanced yoga practitioners

Both apps are android only and are miles ahead of anything iphone can offer which is worth being mentioned imo.