It depends on what you are after.
Of course TrainingPeaks has way more options for analysis like HR decoupling or VI, a huge variety of training plans/coaches and with Zwift you have the social aspect and the eye candy.
But TR costs less and you have a nice designed experience out of one hand. If the TR plans work for you, you won’t need the deeper analysis of TR, because you won‘t adjust your training in your own, based on your analysis.
So I‘d say Zwift is of course designed for riding and if you want to train during your ride, you definitely have the option to do so…