If just one for everything I do it would have to be an 8wt I like the Xi2 it has a strong back but isn't a broom stick. Handles lines from 100 to 400 grain and casts floating like a rocket launcher. You can build it for much less then retail if you don't count your labor.
On the cheap side a TFO TiCrX 8wt or maybe St Croix. I'd also build them as well.