On the official osu! website you can sort by most played or most favourited to find popular songs. You can also download beatmap packs there.

I downloaded the newest version and on max ui scaling text size is at least as big as it is in other apps

It’s only on GitHub. Since it’s the official version of osu! it also uses the official servers that probably have way more songs.

Is there a reason you’re not using osu!lazer?