PrettySammy I have to agree with icaros here. Illusion/Rad over Empathy.
What do I know? - I have Empathy/Dark Defender and a Dark/Rad defender, among other characters and have just started an Illusion/Rad Controller.
Why? - In order to solo or kill a mob it is 75% about killing the mob 25% about recovery time. What do I mean by that? I mean that I need to be as efficent (the amount of time to kill a mob) as possible when killing a mob. Next I need to be able to attack the next mob without a lot of downtime. While Empathy when I finnaly get RA at level 28 will certainly help with downtime that is both too long to wait and really does not help me kill my mobs faster. With AM and EF being available to Radiation it clearly is the superior choice for a Solo or "mob killing" build. That is not to say it is a better choice for all builds like support roles or whatever, it is clearly not as efficent as Rad for soloing and certainly not early on.