Criteria for choosing GPU

Hello everyone!
The time has come to replace NVidia Geforce GT-710 with some Quadro card. I'm using two BMD devices at one chassis to create two different programms and the render power of that card is not enough. As far as i know, Quadro is the best choice for Caspar. How can i determine which one has the best render power - which parameter i need to watch?
Advise me which model i can choose - but not so expensive))))
Thank you!