the 780 is better, newer technology, 290 is just a old tech pushed hard to keep up.
How exactly is the R9 290 'old tech'. The R9 290(x) is the only new card in the R9 lineup; The rest are rebadged HD 7*** GPUs. The same goes for Nvidia. The GTX 7** series (780 and 780 Ti excluded) are just rebadged GTX 6** cards.
yeah depending on the 780 it will stomp the 290, it trades blows with the 290x in some games and can often be found for a little bit cheaper. i jumped from amd to nvidia and have found their drivers to be better and the overall stability to be a slight bit better, though i still really love amd. go with the cheaper card with the better cooler and you can't lose!