Similarly to the Barclays Arrival card, Capital One miles are actually not frequent flyer currency, but monetary currency where 1 mile = 1 cent when redeemed for travel purchases. So this 50k bonus equates to a $500 credit towards any purchase towards flight, hotel, car rental, cruise, etc., making this card generally immune to frequent flyer point devaluations that we have witnessed repeatedly through the years. Redemptions with this card also won't affect your ability to earn elite qualifying miles/points since your travel purchases are revenue fares, unlike award bookings.
Among the other benefits of this card:
-Visa Signature Concierge
-Visa Signature purchase protection
-Annual fee waived for the first year ($59 value)
Be wary that Capital One is known to do a hard pull on your credit from all 3 credit bureaus, which could have a noticeable effect on your credit score. Other than that, this simple card is the way to go, and the sign-up bonus is currently one of the most generous given the spending threshold.