I would say that Rad is better than time. Rad has -def -tohit -res -dmg that are toggles that are AOE. same with -spd -reg -recharge, while time is single target. Rad also has the PBAoE, Team +DMG, +Recovery, +Recharge, +SPD, +Res(Disorient, Hold, Immobilize, Sleep). Also a toggle PBOE hold that stacks mag+2 so bosses will be held.
As stated before all these stack and the more you have the better you get.
I would like to pit a team of Frads against fire/time for a TF race anyday.