It will be depending on the person you are on boarding...
A normie non tech savvy and little to none understanding of the power of decentralization and relay management.
Primal or Damus for mobile or desktop.
A tech savvy individual understanding the above and whom consider his CyberSec as a serious matter:
Android: Amethyst nostr:nprofile1qqs24yz8xftq8kkdf7q5yzf4v7tn2ek78v0zp2y427mj3sa7f34ggjcpzamhxue69uhhv6t5daezumn0wd68yvfwvdhk6tcpzpmhxue69uhkummnw3ezumt0d5hszrnhwden5te0dehhxtnvdakz769wywf , 0xchat
Desktop: nostrudel.ninja