It's hard to name just one, so I'll name a few. When it comes to fighting games I like UNIST, the sprite work in that game is amazing and I think it looks better than other sprite-based anime style 2d fighters like blazblue and p4au. I also love the Azure Striker Gunvolt series for it's outstanding pixel art as well, those games look fantastic. I think Ori and the blind forest is one of the best looking games in general, I love the style, the designs, the colors, everything. I also really like cel-shaded games like Tloz the wind waker and Klonoa 2: Lunatea's Veil.