Best of luck and enjoy your new home!
All the best to you.
Usually the more integrated the appliance is, the higher end it looks and thus fetching a higher price. So built-in > slide-in > freestanding. Make sure you are getting an upgrade, not a downgrade.
I would also get the model numbers of the included range and the upgrade range, find out the market prices of both and determine whether the upgrade cost is reasonable.
On resale after 7 to 10 years market preferences will have changed and the appliances will have had a lot of use. The difference between upgraded appliances and standard appliances will probably not have a great effect on the sale price after 7 to 10 years.
In general I recommend that you consider the upgraded appliances rather than the standard appliances.
The ugraded appliances are usually of better quality and reliability and are usually a small part of the cost of purchasing the property.
If you're looking to sell your property in 7-10 years you're probably going to need to update appliances by then to get the best return on your investment. So I would take into consideration the cost of upgrading now vs. replacement later which will undoubtedly include replacing the kitchen counter top. I would suggest doing a little research. Find out how much it would cost to replace the counter tops vs. what your builder is charging for the appliance upgrade. This should help you make a better decision. Best of luck to you.