The Liberated Borg has Borg nanites which is a health and shield regeneration buff, efficient which is a power buff to the various systems, neural blast which is a stun that goes off and on quite a bit and slows down the target, and cybernetic implants which look cool, but cybernetic implants are available through the seven of nine costume pack for federation females.
The Joined Trill has hyper metabolism which is a health regeneration buff, joined symbiote, and lots of spots. I would say Joined Trills are better for Science Vessels due to the Graviton Generator, Particle Generator, and Subspace Decompiler which all use science bridge officer powers. The other buffs are useful for any ship.
The main problem is whether the skill buffs are decent enough to make a significant contribution for your decision. Personally, I would go with aesthetics. IMO Trill is stronger for space while Borg is stronger for ground. So if you are going Tactical or Engineering, then go with either one, but go Trill for science. Both are interesting characters to play with a far more interesting story than a human or klingon joining Starfleet or KDF.