Long term prospects of pairs

Hello everyone. I am obviously very late to the part. I'm wondering where the best resource are in order to put some capital aside into a long/short position in pairs which will outperform others over time. If anyone has any strong opinions on the subject, I am happy to listen as well. I work as a finance quant so any data or proof is highly welcome also but I understand that in a 1-way market that might be tough to quantify. Cheers!