Both will have CFIs associated with them and will recommend a few for you to talk to. You should talk to a few different CFIs to find one whose schedule and temperament suit you. You can start to fly and begin your flight training immediately. It's not a good idea to change instructors frequently, but it's perfectly OK to try one or two lessons with several different instructors so that you can find someone with whom you are comfortable. There are several different aircraft used in basic training.
Most schools use two seat trainers because of their simplicity and low cost.
Many schools employ the Cessna 152, which is widely regarded as the best primary trainer ever made. The next most common two seat trainer is the Piper Tomahawk, which is also a fine aircraft, but are less common as fewer of them were built. Until recently, new two seat trainers were not being manufactured, so some schools use four-place aircraft for training. These are usually fine as trainers but are more expensive. Their use may be required though when both the student and instructor are large people as the two seaters have limited weight lifting capabilities.