I have seen all of the Matt Smith and David Tennant episodes of Doctor Who. Although Tennant is good, Matt is funny, clumsy, and happy, yet he knows when to be serious. Also, David Tennant was always angry or sad it seems. Now, Compared to Peter Capaldi he's as happy as a unicorn but I'm getting off topic. Matt Smith also has the BEST hair by far. There's no competition there. He is charming, especially when he trips over things and says they are cool.
David Tennant wasn't "always angry or sad". If that's what you really believe then I'd like proof of that please, or argument is invalid. And I also struggle to see what hair has got to do with anything. Doctor Who relies on intelligence and wit to create vibrant drama, not just boyish and stupid antics - which Matt Smith's episodes were nearly all full of. It is clear that Doctor Who remains a "better" (for want of a stronger word) television program when it is dramatic and heartfelt, as opposed to the Smith and Capaldi era when it simply gravitated into a dumb comedy. Tennant brought the dramatic weight, compassion and wit to craft four seasons of television gold. As soon as Matt Smith danced his stupid way onto the scene and Moffat took over the show, Doc Who was damnably dragged through the mud. Remember the height of Doctor Who's power, back with episodes such as "The Girl in the Fireplace", "Human Nature/The Family of Blood" and "Blink"? This was true and great Doctor Who.
That's the thing though! Matt Smith is lighthearted and funny. Doctor who is after all, a family show. That means that it shouldn't always be serious. Matt Smith is perfect for that. He knows when to be serious, and when to be a little more upbeat. I do agree with you on Capaldi though, I feel he's too grumpy and mean. Technically we are having a very pointless argument to be honest. It's all from Steven Moffat. Most of it is scripted, so if you think Matt Smith has " boyish and stupid antics" then blame Moffat, not Smith.