Improv comedy is funny. So is normal, standup deliver the lines comedian comedy. The reason why I like improvisation better, is that it involves more, both out of the actor and out of the audience. In improv, the actor really has to think quickly AND deliver the lines. In standup, all he's gotta do is deliver the lines.
Also, in improv, you have a greater chance of something mindblowingly funny. You just get such strange situations, right? A lot of the time, it's not that funny. Can't make everything funny right? But sometimes......wow, I mean, incredibly funny. So, you take greater risk, but greater reward. I think the reward is worth the risk. Very funny stuff.