Speaking from exsperience, Nuking an AI homeworld is about the worst thing you can do. Even if there are 5k units on it. only 1k will be killed by the nuke, and those where the easy ones to kill. If your thinking of nukes as your option you might consider EMP's. exspecialy if its your last AI, so you would not be woried about AI progress. Me and a friend used this strat on our last AI homeworld (it was the only way). But what we did was build all the lighting warheads, armored warheads and EMP's we could. We then maxed out our reasources to 600K each. we then had our enginiers assist the missle silo (which was stationed right out side the wormhole leading into the AIs home). and had it set to outbuild EMP's. we then sent our EMP's in. The first 4 will add up to give you 2 mins of paralasis, but you will be constantly building more. I found I could build them at a rate of about 1 every 10 secounds. ANd they would give a 30 secound effect. This ran the paralaysis clock up to 20mins before we sent in the first attack (alhtough we could have goten away with 10mins). We then sent a few lighting in to weaken the stuff around the warp in area. (only like 3 or 4 out of the
. Our fleet then warped in and began attacking the stuff at the warpin. (and all the stuff that was imune from the EMP then came to attack us). However before it would get to us we started building turrets in mass (I sugest just the basic turrets as they give the most bang for the buck and are quick to build, as you are probly going tobe low on resources due to making all those missles). have your enginiers assist in building these turrets. dont forget to move in your repair platforms and tugs. Once you have control of the warp in. we then took the remaining missles and sent them by the command station to destroy the defenders there. This pretty much cleared 80 percent of the defenders there. By the time this was done the rushing fleet had been killed off, so we where then able to send our fleet down to attack the shields of the command station. and then the command station itself. Without the AI ever reciving any reinforcment. (which was a must becouse it was geting a new wave like every 1 game minute).
Anyways nukes are just bad. They kill supply to the planet. which means no defenses and no repairing. And becouse of this I think nukes are the most useless units ingame. You dont need them where they will work, and they wont work where you need them.