Deciding between Zendesk and Servicenow. Any feedback on either here? I am in a mid size org. 

I've used http://www.opsmartcm.com/ and have been very pleased with the CMDB & ITSM capability.   SNOW typically ends up being very $$.   

It really depends on what your end goals are. The solutions are secondary compared to your requirements. Do you want just a ticketing system? Do you also want a knowledge base for your team and those you serve for the option of self-service? Do you want change management? Do you want a purchasing module? Do you want incident and problem management? Are you willing to try open source products? Also, given the big financial difference in the two products you selected, what kind of budget do you actually have? I would suggest looking at a few more products if you have all of your requirements laid out.

ZenDesk is user friendly

Depends on your requirements. If you just want a ticketing system for ITSM, Zendesk is probably the way to go. ServiceNow is great, but it can do so much that I almost lump it into the "ERP" category.

MyPOV - Zendesk for external customers; Service-Now for internal customers