Level/Seer HVAC for 1800 sq ft townhouse?

[Daniel Felix]

We are going to be first time landlords in a couple of months for an 1,800 sq ft., 3 floor, townhouse condo. We need to replace the HVAC system, and I believe this is a "B property". 

1. What would you recommend for the SEER rating we get?

2. Any other recommendations?

Thanks!