There are different types of paddles. Some have rubber with little knobs and then my favorite is the wooden ones with a bit of sand mixed in the finish. I find these the best for spins. But I know it is a matter of taste. I can get a spin on just plain wood, but it takes practice.

Most modern table tennis / ping pong paddles (also known as bats or racquets) have red rubber on one side and black rubber on the other to comply with ITTF regulations. A rubber sheet that is smooth is known as an inverted sheet. If the pips are exposed, it is a pips-out sheet which may be long pips or short pips. The surface with the most spin is the inverted or smooth type. If both sides are of the smooth/inverted rubber, here is what I would suggest to determine which side produces the most spin under very similar conditions: Place the paddle on a ping pong table such that the black rubber is flat on the table and the handle extends beyond the surface of the table. Stand back about 3 feet and toss the ball such that it bounces off the red rubber, then bounces on the table at least twice. Try to toss such that there is very little spin. Observe the spot where the ball bounces first, and where it bounces a second time. Measure the distance between those fist two bounces on the table. Now turn the paddle over so the red rubber is on the table and repeat the bounce of the ball, this time striking the black rubber, and again observe the locations of the first and second bounce of the ball on the table, and measure and note the distance between the two bounces on the table. The greater the distance between those two bounces, the more spin the rubber produced. Here is why: when the ball hits the rubber at an angle, the rubber grips the bottom edge of the ball, causing it to have top-spin. When the ball hits the table with that top-spin, it gets a forward boost. The more spin, the more boost, and the farther the ball will go before that second strike onto the table. Repeat this many times on each side of the paddle, trying to make sure you toss the ball the same way each time. The distance between the two table bounces is also greatly affected by how hard the ball is tossed, as well. For more information, search the web for table tennis rubber comparison and you will find charts that rate the many available rubber sheets by spin, speed, and other factors.