Session doesn't store logs on a central server. They are encrypted and stored on lokinet.
Anyway other options are: Jami, Signal or Molly and maybe matrix. Keep in mind Briar will drain battery a bit and doesn't receive notifications offline unless you setup a dedicated device
session tries to promote their oxen cryptocurrency and lokinet which imo crypto currency are used by baiters to bait people into ruining their money
you dont understand what signal /molly is , do you ? they are centralized server and OP specificially asked not centralized server / server for that matter
matrix is good but it still need server , plus matrix.org takes quite a bit of metadata
jami's good but it uses turn server to verify your name
briar's bluetooth functionality can be violated plus no good ui/ux
uhh i linked you the website source , no offense but its written there
also i hate crypto so maybe thats why i am picking up on those guys specifically i guess