My own own choice would always be the WiFi & Cellular model of any iPad in preference to WiFi Only. Whilst I infrequently need direct Cellular connectivity (I generally use the iPhone hotspot when if working remotely), here is the reason why...
A WiFi Only model of iPad can connect to any compatible WiFi network or cellular hotspot connection (e.g., a Cellphone or Cellular Router such as “MiFi”). As such, using a hotspot, an iPad can benefit from a Cellular connection. If using an iPhone, connection to the iPhone hotspot can be automated - such that the iPad will automatically enable and connect to the iPhone hotspot when/if needed.
However, always consider you potential need for GPS positioning capability. If you would like to use “mapping” Apps on your iPad - and would benefit from accurate determination of your location (for example, a moving map) - then a WiFi Only model of iPad might not be the best choice as these models do not have any GPS capability.
Only Cellular models of iPad incorporate GPS features, GPS functions being an integral element of the iPad Cellular chipset. GPS remains functionally independent of Cellular connectivity; it is not necessary to provision cellular service to benefit from the GPS features.
WiFi Only models can only “infer” their location from a database lookup of neighbouring WiFi networks for which the geographic location is known, or the geographic location of your public IP address. For static applications in urban locations, where the location of IP public IP addresses and WiFi networks are known, an “inferred” location can be relatively accurate. However, in rural locations, or when using a Cellular/Satellite/VPN connection, location accuracy of an inferred location [if it works at all] may be very inaccurate.
So, there you have it. Notwithstanding the above reasoning, the WiFi & Cellular model also provides flexibility in the choice of iPad network bearer - whether or not you have access to a WiFi (or MiFi) hotspot connection.
As an additional “edge” case, I occasionally need the iPad to host a closed WiFi LAN network between it and peripheral devices - whilst maintaining a WAN connection via Cellular; this arrangement isn’t otherwise possible when using a WiFi hotspot.
I hope this information and insight proves to be helpful in informing your eventual choices.