Which one do I think is "better?" Come on man, give me a scenario here. Basically everyone here has said each has their disadvantages and advantages, so I won't re-post that, but at points one is "better" than the other and at other points the other one is "better."
If you're asking which one I find more effective generally, I'd say the kick serve tends to throw me off my game a bit more, but I can't answer the question to my fullest without you elaborating a bit.