Eric
There a lot of great tool manufacturers out there - Onsrud, Vortex, FS Tool, Amana, Southeast Tool etc etc and many are doing various coatings. Just as important as the tool itself, is dialing in your feed rate, RPM, and set up. Make sure you have good quality, clean tool holders and collets and you are setting them up with a torque wrench and set up stand for consistent, accurate set ups. Reducing run out and calculating proper feed rates/ rpm's can drastically improve your tool life and cut quality. Talk to your tool service rep or the tool manufacturer if you need help doing this or you can find it online - heres one reference :https://www.onsrud.com/Forms/Cutting-Data-Recommendations.asp
Regarding Resharpening:
Talk to the company sharpening your tools - let them know that you are noticing a significant drop off in tool life after resharpening. Maybe they can tweak their process - if they are only grinding on the OD then they can grind the inside flute, or vice versa or both. I think it is common to expect somewhere around 10-20% decrease in tool life after service because of reduced diameter, clearances and flute depth. If they arent properly equipped to service the tools then maybe they are able to send them back to the manufacturer on your behalf for factory service.