My favorite peppers to grow are my own. Every year it changes but I really enjoying growing peppers that I have created. It's exciting seeing what pops up. Last year my favorites were my Shishito bubblegum cross, TFM scotch bonnet bubblegum cross and a crazy cross of (pink tiger x cbbg) x peachgum that came out carrot orange with one of the best flavors i've ever had in a pepper.
Just for looks I would go with SBS purple, that's a dead sexy pepper plant.