That's an interesting choice. I wouldn't buy any of them, but if I had to I'd pick DOGE. XRP is a centralized coin that is worth nothing. DOGE at least funny and decentralized.
No bad fun here XRP and Dogecoin are two very popular coins. If I had enough money to invest I would definitely invest something in both of these coins. But I always believe that all these coins will occupy good position in future. Maybe many people may not like these two coins but these two coins are very popular for me.
I do think that XRP does have more potential than DOGE, however, both have much to think about what their future would be, ideally. Only time will tell. It's better to hold more of a coin that has more use cases, in my opinion.