Prima Luna or sonic frontiers or audible illusions

I have an audible illusions 2d. It has served me well for many years. But, it seems I have the upgrade bug of late. I am looking to increase the imaging if possible of my system and am curious if upgrading to the modulus 3a would be a significant improvement. Or, would I be better served with a sonic frontiers sfl1 or line 1/2? Lastly I have to admit that the prima Luna prologue is appealing bc of the exposed tubes. Not sure on the sound though...any advice? Any other choices that have the tubes on display?