We've got some C3KX-NM-10G modules coming for our 3750x stacks, one stack in each rack, and are looking to uplink them. The racks are side by side.

Each rack has 2 3750x stacked. We figure we'll do 2 uplinks, 1 from each switch in each rack to each other in an etherchannel.

The question is, I see all these different types of 10G optics to go into the module. The module itself has 2 sfp and 2 sfp+ ports.

I see:
SFP-10G-ER
SFP-10G-LR
SFP-10G-LRM
SFP-10G-SR
SFP-10G-ZR

Seeing as the cabinets are side by side the obvious choice appears to be SFP-10G-SR. But is that really the best choice?

EDIT: Also is there a reason to buy new Cisco vs. used Cisco vs. new Third party?