The C.A.D.S. series by John Sievert

Didn't see this series mentioned.  John Sievert was a psuedonym for Ryder Stacy, aka Ryder Syvertsen and Jan Stacy, and David Alexander.

The basic premise is that the U.S. was developing powered armored suits for nuke warfare and the U.S. is nuked by a surprise Soviet attack and invaded.  The Soviets have their own power suits developed from stolen technology prior to the war.  The U.S.suits get a few upgrades as the series progresses, the US testing/development facility survives the attack.  The latter ones have an AI that can take control of it if need be when the operator is in it.  Recommended if you want a post nuke series with powered armor and some high tech units mixed (helicopters that have lasers as the main weapon, etc.).

List of all 12 books in the series in order:

C.A.D.S. (Computerized Attack/Defense System)

Tech Battleground

Tech Commando
Tech Strike Force
Tech Satan
Tech Inferno

Doom Commander
Cybertech Killing Zone
Suicide Attack

Recon By Fire

Death Zone Attack
Tech Assassins

For some reason book 10 Recon by Fire is omitted on a few lists of the books in the series.