We tried the following and these were just my personal opinion of them. Keep in mind that fillings change the taste of the cake. They are also in order of what I liked best to least.
Cake:
Carrot - Nice texture, slightly spicy (as in spice cake not hot sauce haha)
Orange - Very moist, full citrus flavor
Marble - Typical marble cake
Almond - More almond flavor than I anticipated, very nice
Red Velvet - Nice texture, subtle taste
Vanilla - Typical vanilla cake, slightly dry
Chocolate - Tasteless, kinda dry, no chocolate flavor
Fillings:
Dark Chocolate - If you love chocolate this is for you! (very well when paired with the marble)
Mocha - Nice coffee flavor (amazing when paired with the carrot, very holiday flavored combo)
Tropical - Sweet and fruity (nicely paired with orange)
Baileys - Very similar to the mocha but with a subtle liquor taste (goes well with the vanilla)
White Chocolate - I hate white chocolate but this was fantastic (goes well with marble or red velvet)
Almaretto - Heavy liquor flavor (goes well with almond or orange)
Orange - Heavy artificial orange flavor (goes well with vanilla)
Raspberry - Heavy artificial raspberry flavor (goes well with chocolate or marble)
Butter Cream - Heavy sweet flavor (goes well with red velvet)
Cream Cheese - Very bland (goes well with red velvet)
Bavarian Cream - Slightly watery consistency, very bland (didn't go with anything)
Blackberry - Very bland (didn't go with anything)