You're missing another model, the K3S. That said the Plus model all the way. The K3S has a way better screen then both the RS97 and K3Plus but it lags badly on tons of emulators and has no love for CFW. It has the same SOC as the RS97 and K3Plus BUT the higher screen resolutions makes it lag badly on bunch of emus.
Anyway, just get an RS97 instead, haha.