I have used Stock only very shortly. But as @OKSun wrote, its initial bugs are being sorted out. So If you are after the full 'as-Google-intended' Android experience (with all pros and cons attached), stock is probably what you want.
If you want an Android-like smartphone experience, but intend to use mostly FLOSS software, go for LineageOS (and best avoid installing Gapps et al.). This will allow you to use all Android apps listed on F-Droid plus many free ones from the Play Store (although most are not FLOSS). Some Apps relying on Google services may not run though, even with Gapps et a