"I never had a bad experience with booking.com. Would recommend.
However, I had the somewhat strange experience of making a reservation through agoda.com but the (first) confirmation email was from booking.com. Later, another confirmation email arrived from agoda.com with same info. They have some cooperation I guess.
So it is possible to be booked through booking.com without knowing :-) "
Booking.com and agoda.com are both owned by parent company Priceline