[jpfed]

Every time you switch, remember what that implies about your weighting of what's important. If you force yourself to develop a consistent weighting of criteria- or even just to let your weighting of criteria change in a consistent direction- then you won't cycle back to previously-discarded solutions.

So when you say that B is better than A, get specific. "If I choose B over A, I'm saying that testability and straightforward implementation are more important in the context of this project than concision. Is that true?" If it's not, keep A. If it is, remember your choice! Then when C tempts you, you can ask yourself- is switching to C consistent with the weighting of criteria that caused you to switch from A to B?

Perfect software doesn't exist. But you can try to best match your implementation to the particular concerns of the context it's written in.