I really can't pick just one. The ones I've made the most are the tiramisu and the lemon macadamia.
The tiramisu is my personal favorite of the ones I've tried. I've made the chocolate with PB frosting and chocolate ganache as well and that one is probably my second favorite. But I wanted one I could make ahead, and to use a recipe I haven't made yet. The lemon macadamia could be a good choice since my husband loves macadamia nuts.
Keep the suggestions coming!