One very important thing to keep in mind is if any repairs will be needed with this iPad, that your friend will need to either take it back or ship it to the U.S. to get it serviced. Apple's warranty is not universal internationally. You would be better off selecting the iPad that you would like to gift them, and then, send them the funds to purchase it themselves via the Apple brick-and-mortar store (in available) or the Apple online store using a credit card from that country.
Which specific iPad would really come down to what you believe they would use it for. Just about any iPad model will work for most general uses. The iPad Pro would not necessarily be required either, based on those uses.