i want to build a site, which theme can i use?

this is the first site am building with wordpress, i want to switch my themes, to buy another themes, the theme am using on my site is giving me problem,
i have structure data error on google webmaster, which is droping my earning on google adsense, i cant fix it so i want to buy a new themes for my site, am using bpress and another classified plugin in the site, which themes can i buy, here is my site