Are you willing to overclock? Is sound and heat import to you? Do you need it NOW or can you wait? I ask because the R290x apparently doesn't overclock well, and gets really hot and loud, but if you were to wait until there are some nonreference models with better coolers it might improve. Of course if you water cool your graphics cards that could fix both those issues, http://linustechtips.com/main/topic/71385-r9-290x-water-cooled-overclocking/
this was all that I could find for water cooled 290x benchmarks, but more will come I am sure. The 780ti according to early "leaked " data, so take that with a grain of salt, seems like it could have more room for overclocking, and, seems to perform pretty close to, or better than the Titan, 290x and 7990 ( I can't remember the specifics). What I would do is wait a little, look at real 780ti benchmarks and overclocks, look at nonreference 290x benchmarks, temps, and noise levels, (water cooled and not), and then weigh what is more important to you, sound, heat, performance, and cost. Not much of answer, sorry, but things to consider.