i would pick a gtx780 over a gtx titan any day of the week. even more so for the soon to be released gtx790.
i prefer dealing with a either evga or asus.
both of the top nvidia cards are overpriced though and the radeons are typically good value so its worth looking into perhaps.
in any case... just about any of the high end cards will run high end games 3 years from now however not at maximum settings. this is impossible to guarantee as the next gen games could crush any current card. if you lower the settings a bit though anything should be playable even on a gtx770 level gpu (or even lower than that in some cases). just pick something at your budget level.
if you dont need a gpu quite yet perhaps wait for the 800 series to come out from nvidia.