Yes, the GC3 is generally considered to be a better launch monitor than the SkyTrak. It is more accurate and provides more data, including ball spin axis and club path. It is also more durable and has a longer warranty.
However, the GC3 is also more expensive than the SkyTrak. It is about $1,000 more in the United States.
If you are looking for the most accurate launch monitor possible and are willing to pay the extra money, then the GC3 is the better choice. However, if you are on a budget or are only looking for a launch monitor for casual use, then the SkyTrak is a good option.