I used Viagra for 3 years. It will give you great results when timed properly. For me, I popped 1/2 pill about 1 - 2 hours before the action was to begin. I was good to go for a few rounds and for a few hours. It seemed to delay but ENHANCE my "finish" also in a major way!
Now using Cialis. With Cialis 1/2 pill lasts me a solid 48 hours - sometimes longer. So, if I take one around 8:00 PM on Friday nite, I am golden until about Sunday nite, sometimes Monday AM. But, Cialis does not give as intense an erecton, nor does it seem to delay reaching the "finish-line", as Viagra does. It does begin near immediately, so if I sense wifey is getting excited, I just hit the bathroom - pop 1/2 Cialis - and by the time I'm ready to pull out the jammie it's already ready for me.
Cialis does give me headaches also. A dull, constant pain that sometimes comes on immediately, other times it begins about 12 hours after taking the pill. As for nasal congestion - never experienced that from either.
So... In a final analysis: If you want a solid, tube-of-steel for a few hours, go with Viagra. If you want a great weekend w/out worry about performance, go with Cialis. And, Viagra gets me ready for action again very fast, Cialis does not.
One thing that I personally notice is that the "finish-line" is very pleasurable and intense with Viagra. That is not the case with Cialis. After my current Cialis Rx is done, I'm going to switch back to the big "V".