I would say that both the security apps are best of their kind, with many detection domains overlapping.
Zemana has PUA, keylogging detection and system apps scanning that's a good one, appreciate it.
Still, I would prefer only one anti-malware app guarding my smartphone. Maybe you could uninstall Bitdefender if it is not for the anti-theft protection.
Adguard is limited to Samsung browser and Yandex browser only, I checked it on PlayStore.