As long as your blog has great stellar content and you place the ads in the right places such as in the blog posts, and in the sidebar then just about any free wordpress theme will do.
If you can afford too though I would recommend getting an Adsense Optimized wordpress theme that is really professional and pay the money for it.
That money you spend will make your blog look more professional and trustworthy and increase your income by increasing the amount of Adsense clicks you get.