You're taking a vote?
Discrete, of course. Whether solid state or tubes is up to you.
Opamps score well on bench testing, but don't sound as good as discrete in the long run.
I imagine that Pixie & blmn will weigh in in favor of specs, here.
Opamps have one thing going for them. You can whomp up a circuit in no time using them as building blocks. Consider the possibility of throwing something together out of opamps to get you by while you design a more elaborate discrete circuit. I made a quick-and-dirty crossover a month or two ago with some LF353s I had on hand. Later, when I had more time, I went through and did a better job using MPSA18s and 2N5457s. That was also a quick-and-dirty, yet sounded noticably better than the opamp crossover, even without optimizing--which I still haven't done. (I've had 48 hour days on order for forever now, but they still haven't arrived...)
If it's the power supply that's slowing you down, consider using an unregulated one for the time being. Although I personally believe that regulated is the way to go, I'm also prone to getting something up and running in a hurry, but making the design modular so that I can drop in upgraded designs or components later. It suits my schedule better, There are simply some days I want to sit down and hear music, even if it's not optimal. Besides, doing it this way gives you the opportunity to learn exactly what differences opamps make vs. discrete components, or regulated vs. unregulated.
Grey
I often wish that the op amp makers would offer an 8 pin dip package of simply a pair of matched JFETs used in one of their BiFET op amps.
