In this article you can know about the best source to download android apps .friends before writing anything i want say you that 100 percent safe apps is best apps and if you get virus then that is froud so it should be clear that i am writing only safe source not all.
According to my personal experienced 9apps is very bad source to download apps because there are lot of fake apps available there.
First best source is apk mirror
You can download apss from apkmirror website.most benefit is,you can get beta version apps on this site,means if you didn’t signup beta user on playstore then you can download from here i.e apkmirror
Second source is apkpure
Yes apkpure is just like play store all the apps available on play store is also available on apkpure site.you can also get offline file of play store on apkpure site.just pur url of play store in apk search bar and you will get download link for apk file whicha can be useful when you distribute or re install apps.
Friend. All the source is tested by me but again in last i am saying that if your priority is safety then always download apps from official play store only.