Okay so I have two options a 96 infiniti Q45 or 96 Monte Carlo z34 which one should I buy?

If this is the two cars you narrowed it down to it is totally up to you. Just remember that the Infiniti is going to have lesser places to buy parts and service as the Chevy would. Also you have a two door over a four door. So it could depend on what it is going to be used for besides normal transportation.