IMO, the bars improved body roll by quite a bit. From stock I remembered feeling like the car was going to flip on its side when I went around round abouts at 'normal' speeds. I went to Sway bars and Lowering springs, gave me more confidence and could not feel the roll much when travelling at 'normal speeds'. After I installed coilovers and a few more bars I can accelarate through them with little body roll.

From that I would say if you just want better handling at normal speeds, then getting the bars, would be enough and cheaper. To be able to do a bit more spirited driving, get coilovers, but I think might cost twice the price of bars.

For me the bars and coilovers are worth the handling improvements and the loss in ride comfort to me is still at an acceptable level.