In terms of performance, OCing potential, less noise DirectCUII has distinct advantage. If R9 290 is 4GB then grab it and use SP fans fo good air flow. R9 290 runs much hotter than nVIDIA counterparts. Better grab Vapor-X than Tri-X for better cooling in Sapphire.
Ah then I would definitely get the 290 instead of the 780. Unless you want some of the nvidia specific features. The performance between them is quite close.
In terms of performance, OCing potential, less noise DirectCUII has distinct advantage. If R9 290 is 4GB then grab it and use SP fans fo good air flow. R9 290 runs much hotter than nVIDIA counterparts. Better grab Vapor-X than Tri-X for better cooling in Sapphire.