Whether you intend to to use the Cellular functions of iPad, or not, the WiFi & Cellular model is always the better model to own. The Cellular models have significant functionality that is otherwise not present on WiFi Only models - specifically, it has GPS functionality, this beeing needed for accurate Location Services.
The usefulness and importance of GPS capabilities with iPad, at first glance, is often underestimated.
Without GPS, your iPad relies upon “lookup” of your IP Address and neighbouring WiFi networks - in an attempt to infer your location. Whilst this method of determining your location can be accurate in urban areas, it often inaccurate (if it works at all) in rural or unpopulated areas. Many iPad users discover this the hard way - and are disappointed when many services (not just mapping) fails to work as anticipated.
I hope this additional information is helpful to you.