What DB6 said.
I've flown both, and they are different. you can learn well in either. The Cessna is tougher, and will tolerate poor runways better, the Grob is a delight to fly, very precise. The constant speed prop is a complete learning non event. You could fly it with the propeller set to full fine nearly all the time, and it would not matter, but you'll quickly learn the pleasure of being able to coarsen the propeller pitch. Do fly both at some point of your training, just to learn the differences.