four artillery units, flame thrower units and grenade units and a couple of gunships should do the trick. Most force users can be taken down by this force.

"It's a force user! Concentrate fire to suppress that sucker and call in the artillery and air force to finish it off! Send in the flame troopers. Any trooper coming back with grenades gets latrine duty!" Unknown clone commander during operation Order 66.

CIS kinda suck on defense, but there is a way to make it work:
-Base shield on key worlds, with a couple artillery sitting behind the shield.

-1 droideka squad to rush-cap nearby zones and build field bases/turrets to slow the enemy down.

-Finally, a huge amount of air units. MAF's or HMP's both work well, but HMP's are overall better imo.

Make sure to send factory-built units to the front and don't just let them sit at the base. Be aggressive in the defense.
Air units are gonna be where most of your attention is. Keep them micro-managed well, hitting hard, but pulling back to a repair station when things get threatening. Just keep your ground units focused around chokepoints. Pause often to issue move orders.

Jedi are worthless vs air units of any kind, and most units lack anti-air modifiers meaning their shots do not hit as accurately as they would against ground vehicles. Beware AT-TE's and Juggernauts, as they do have anti-air. You can still use air units against them, but you have to be a bit more careful.

If you can't afford a slot for base defenses as a building, then make sure to build something useful on every build pad you can find. Those turrets aren't great on their own, but they add up over the course of a fight, and can fill gaps in your ground forces. Even with strong air units, 2-3 anti air turrets spread out across the map will help stop bombing runs if you can't get a planetary shield.

CIS is more attack-oriented, so fighting on defense is where they're at a disadvantage, but it is possible.

Generally you don't want to use infantry against Jedi, because they actually heal a bit if they get attacked by infantry.
You want to use anti-infantry vehicles.
The STAP would be a great option against Jedi especially.

Damn. Thanks for all the good advice guys. I'm kind of out of isolated planets I have to defend at this point unfortunately but nonetheless, I will keep these tips in mind going forward.