In the current situation, what Orochi did is worse.
In a fair/equal situation, where both the users (Tama & Orochi) and purpose (human experiment & fighting for freedom) is equally good/nice, depriving someone their will is worse than depriving them emotions. Especially if it's linked to 21 century earth.
To combat Tama's slightly doubtful method, Oda will make the slave have the ability to resist their master, so in the end it won't be that bad of enslavement.