Funny how they buy more numbers of a really good and well proven airplane that still has tricks up its sleeve. The 15 can be just about as stealthy as the 35 and have all the same avionics plus the look around and look through capability.
It goes further and carries more and of course it should since it is a bigger airplane with two engines that could be upgraded.
You also have the F-15 “Silent Eagle” which is an excellent plane which has stealth features which could be an option.