Should You Hit or Loop the Backhand?
This depends partly on your level. Beginners should learn to hit their backhands first. However, it’s also important for players should learn to loop early on, so as to develop good habits. So it might be a good idea for beginners to learn early on how to open with a backhand loop against backspin, followed by backhand hitting against the incoming block and the rest of the rally. A backhand loop against backspin, followed by a backhand hit against an incoming block, is a very strong combo.
I do recommend learning to backhand loop against backspin. It’s good to be able to hit against backspin, especially against a short ball, but a backhand loop is more consistent and takes control of the rally, as well as setting up your follow-up attack. And it's better than just pushing over and over, which gives the opponent the chance to attack and take the initiative.
At the intermediate level, backhand loops are mostly done against backspin. However, as players approach the higher levels, more and more players can backhand loop over and over during a rally.
Backhand looping over and over in a rally takes a lot of practice. On the forehand side, the ball is taken from the side, so you have a large hitting zone. (“Hitting” here means where you contact the ball, not a backhand hit itself.) On the backhand side, the body is in the way, so there’s a much smaller hitting zone. Contrary to what some believe, backhand loopers need great footwork to get their hitting zone to overlap with the incoming ball. The faster the ball is coming at you, the more difficult it is, which is why it’s generally easier to backhand loop against backspin than against an incoming topspin or block (which usually come at you faster).
At the highest levels, backhand looping dominates. USA Team Member Sean Lonergan wrote in his blog at the 2008 Worlds, “The Backhand Hit is Dead.” At the world-class level, nearly every player loops on the backhand side. (Even penholders backhand loop now, using reverse penhold backhands.) The extreme topspin in a loop gives the shot consistency, allows you to loop with great speed as well as spin, and puts your opponent in a difficult position. A backhand hit doesn’t have as much topspin and so there’s less margin for error.
So if you are aspiring to be a world-class player, then you would want to learn to backhand loop over and over. However, if you are aspiring to, say, win a senior event or reach a strong level that's somewhat lower than world-class, then you might want to focus on backhand hitting, while learning to backhand loop against backspin. (If you develop a good backhand loop against backspin, then later on you can learn to loop against topspin as well.) You might want to develop a good backhand loop against backspin and follow that with a backhand hit. (Here's a Tip of the Week on that - "The Backhand Loop and Hit One-Two Punch.")
So what is the answer to your question on whether you should hit or loop on the backhand? It’s your choice, based on your abilities, goals, and preferences.