I have not played either of these great games yet, so I really can't offer a valid opinion.

However, I'm interested in what the gamers who have played both game have to say about the two. If I had to bet on which game is better, since Capcom is behind Zack & Wiki, I would probably go with Zack & Wiki. Both games look terrific from what I seen, and reveiws have been great for both games.

Which game is better? 

Both are equally great, I can't really judge them comparitively, Layton has more straight forward puzzles, but it doesn't have the lovability of Wiki.

I've played a lot more of Layton than Zack & Wiki, but I wouldn't say that the games are directly comparable. Layton is basically a series of logic puzzles that are otherwise unrelated to the story that links them together; as far as I know, the puzzles in Zack & Wiki are directly related to the events and the environments as they are encountered.

I just finished Layton tonight (except for the bonus puzzles 131 - 135, they are tough!), and Z&W is one of my 2007 faves.

They are both fantastic puzzle games. Layton's puzzles are straight forward brain teasers and logic puzzles, while Z&W is a very unique Wii-centric take on a point and click. I'd give both almost perfect scores for what they are, and I couldn't really choose one over the other. They really do both deserve the high scores they've gotten.

I know there is nothing out like Z&W, what is out there similiar to Layton?

Well, I haven't played Layton but seeing as how Zack and Wiki is merely punishing guess and check I can't really say I recommend it. I'm not sure why people enjoy not being able to make a mistake at the risk of starting over when you have no idea what will happen most of the time until you try. The items you get to prevent starting over are limited and cost you. I think I'd much prefer logic puzzles that require thinking and not just guessing and pointing at random spots in the environment to find what you need to proceed like Zack and Wiki,