What styles usually turn out the best
 

out of the homebrew kits?

That depends on what temperature your fermenting at, and more important, what you like. Most kits are well established styles that produce good beer in normal conditions and great beer in perfect conditions.
Personally I have not had one I did not like, but again it depends on what style you like.

When I has doing extracts the best one was always a Belgium Dubbel. No Idea why but it won third place in a local comp here and all the others never quite amounted to anything. But this is just from my experience. ;)

My last one always seems to be the best one, regardless of what style it is

It depends on the skill of the brewer. Any recipe or kit can be great or suck, depending on how much care, attention and skill the brewer puts into it.

If you want to know what people''s favorite kits are, I do believe there are 2-3 hundred threads on that topic.

http://www.homebrewtalk.com/f37/what-some-great-session-beer-kits-127221/?highlight=favorite+kits

http://www.homebrewtalk.com/f39/what-best-recipe-kits-126097/?highlight=favorite+kits

http://www.homebrewtalk.com/f37/good-extract-kits-102574/?highlight=favorite+kits

http://www.homebrewtalk.com/f37/your-favorite-kits-99579/?highlight=favorite+kits

And many, many more threads....do an advance search for favorite kits and choose "search titles only" and "show results as threads."

We don't really get these kits in NZ. Just Muntons, Black Rock, Lion and Brewcraft.

hey u know that thing called the Internets. it has what u need :p

j/k but mail order is ur friend in thees situations

Im loving the Hanks Hefe kit from Midwest

If you read Designing Great Beers by Ray Daniels it would give you some ideas about how to create your own recipes. I opened up my world of beers. The most influential brewing text I've ever read.

If you use the search like I suggested you will actually find threads specifically discussing most of those kits you mentioned...I saw 2 threads about brewcraft kits that I recall and at least one muntons...didn't look at all the threads there may be threads on the others as well...I just culled for you the generic kit threads...but there is a ton more.....