Nowadays I am flying for a major airline located southern Europe. Our SOP call for a RTO executed always by Captain regardless is PF or PNF cause of while on TO run he/she keeps his/her hand on throttles. Spoilers are also close to Cpt position. CPT, usually at LHS, is in comand and takes the decision. When flying as PF the malfunction will be call by copilot and the decision will be CPT choice, when acting as PNF Captain will call the malfuction and make the decision.
Same critera is used for GA procedures.
I have been rated in 4 airplanes and trained in 2 different TRTO and there was always the same policy.
REGARDS