What Is The Best Baby Gate To Use At The Top Of The Stairs??

My son is 7 months now and he is just starting to kinda crawl. We are going to baby proof the house now before its too late. What is the safest yet affordable gate to use at the top of the stairs? We live in a rented house and cant drill in the walls. We also want a gate with a swing door feature for accessability. Thanks . . . I dont know where to begin!!