I heard that 1440p monitors still did not hit the market with true 120Hz.
If this is the case and I missed any news that some exist, then I would get 1080p 120Hz monitors. No need for the little extra difference with today's anti-aliasing technologies!
120 frames per seconds helps getting rid of tearing without using v-sync and it makes going trough the desktop much smoother and relaxing to the eyes!
I humbly think that only a jump from 1080p to 4k and above is worth it!