I love sync and it's been my go to app for a decade across reddit and Lemmy, but I find it's advertising and pro features far more frustrating now than ever before.
The dev also takes long breaks but I don't mind this as his work while he's active is really really good and fast.
If you already use revanced manager for YouTube or other apps, there is an ad free patch for an older version of sync which has an easy APK to seek out, which is recommend.
There is no best. My recommendation is to download a bunch, then uninstall them one by one until you end up with the one that you like best. I settled on my favorite, and I had to give up some great apps with great features to get there. What do you value in a forum-style app?
That's what I use. Didn't want to influence your decision, but there's no harm in revealing it after the fact. I do feel like I missed out on some cool features from the other apps I tried, but Eternity was the complete package.