MaitaFor myself: I would only choose the LinkIt board if I had a specific project that required GSM/GPRS comms. That's a requirement I generally go out of my way to avoid because of the ongoing expense.
Add on that I think the Grove starter kit is mismatched to the buyers of the LinkIt. The LinkIt is going to appeal to someone who is willing to have ongoing expenses for a sim card for their application. That means they probably have something specific in mind, a real-world task they need done. So choosing a sensor kit that is oriented towards easily accessible learning rather than practical use seems wrong to me. One example: someone who needs both an orientation sensor and GPRS is probably going to demand a 9dof sensor instead of the 3dof included in this kit.