What do you admire or dislike about Rainsford?

While Rainsford may be foolish to go so near the side of the boat (an event that causes his fall into the water and eventual capture by Zaroff), there are quite a number of things about Rainsford in Connell's "The Most Dangerous Game" that make this world-renowned hunter admirable.
Perhaps what I admire most is that even though Rainsford loves to hunt, he has no desire to compromise his moral code by hunting humans. Even though he is on an island under circumstances that would never allow anyone to know if he were to join Zaroff, it never occurs to him. His integrity is not governed by whether or not someone is watching, but by his unshakable sense of what he knows to be right.

“Tonight,” said the general, “we will hunt—you and I.”
Rainsford shook his head. “No, general,” he said. “I will not hunt.”

Another thing that I admire about Rainsford is his ability to think creatively even while running for his life. While running, he is able to come up with unusual methods not only to protect himself (like climbing the tree), he also adopts methods of defense to remove threats against him (such as Ivan) and engages in unique offensive tactics.

“Rainsford,” called the general, “if you are within sound of my voice, as I suppose you are, let me congratulate you. Not many men know how to make a Malay mancatcher."

Finally, though Rainsford initially experiences a moment of panic, he is able to work past it to do whatever he can to protect himself and survive.
Ironically, while Zaroff looks to find the "most dangerous game" in capturing and hunting unfortunate sailors, Rainsford's abilities to adapt and strategize make him the most dangerous game.