I've been on both. Humira kept my Crohn's in remission but did not help enough with the joint pain. My drs said they can't get it approved weekly, although tons of people do, so not sure what the deal with my drs is. Cimzia does not last the full 4 weeks for me and we've even tried half a dose (one shot - 200 mg) every 2 weeks and that's not working either. It worked great when I got it on a clinical trial and we got 400 mg every 2 weeks. Not only is my arthritis still flaring, but I'm having a lot more stomach pain and believe the Crohn's is coming out of remission. So, I'm in the process of switching back to Humira.
Both cost about the same with the co-pay assistance programs. Both have the same side effects for me - injection site whelts and I used to get frequent URIs but the prednisone must be keeping those at bay right now.
Cimzia also burns but not as badly as Humira. But, Humira is injected quicker, so it's over faster. I think the pros/cons pretty much cancel each other out and I consider the two to be extremely comparable.