Before you look at brand and best, you have to note that there are two different types of types of splines for defenders depending on year.
As for brands, can't say any is best, there are many good quality manufacturers like Momo, Sparco, Mounty to name a few. Styles of wheel will depend on you and your taste. If you are shortish and like a lighter turning effort, you would want a wheel that's lower to the indicator stalks and closer to a stock wheel diameter.
Depending on how tall or short you are, the steering wheel height will determine comfort and effort too. I am tall so will go with a smaller wheel which sits as low as it can on the steering colum splines. I have one which I acquired in a package purchase, I don't like the height nor wheel thickness but will machine a spacer to make it sit lower.
Spacer will sit at the bottom of the hub with wheel below...not a conventional set up, but it will work for now if I don't get one before the end of my rebuild.
There was a thread here quite recent as well regarding steering wheels, you should do a search.