You really need to do a detailed check against ProTools Ultimate to make a judgement, plus there’s the annual licencing fee to consider. Apart from the post features, the biggest difference is in MIDI and VIs (assuming you are a composer who makes use of this). Tools is still very basic in terms of MIDI/VI control, Nuendo has all the features of Cubase but of course this in integrated in the one Nuendo platform. The Avid cloud features are excellent, but you have to pay through the nose. Editing, mixing and assembly is very slick in Tools, ditto the bussing, VCAs etc - is really far more oriented to the ‘mix engineer’ and live band tracking overall. Having said this, Steinberg’s Control Room is pretty hard to beat.
Another consideration may be where you live and work. If America /LA, the ProTools thing is pretty strong and being able to easily open and work on those sessions by others may be important buisness-wise. Accross the rest of the wolrd (there is one), not nearly so much & I continue to exchange with other DAW owners, eg: Studio One, Logic, Ableton Live etc. My copy of Tools is only really retained for such backward compatibility, but not so much these days. Nuendo has AAF, but not Cubase; however, Tools round trips much better with NLEs (video and audio), Nuendo is still very basic there but there are other options apart from AAF which work fine (eg, NLE export mult-track audio videos).
Personally, I’d go with Nuendo. Better company Yamaha/Steinberg, plus the Nuendo interface is much more familiar in terms of transiting from Cubase. Hope that helps.