Overall the Torva will probably be lest costly as you'll need to purchase RuneScape gold a completely different pair of Malevolent quite often to keep up with how fast it'll be degrading. If you plan on strictly bossing, then I'd think about a pair of Malevolent, but just remember that it's gonna turn to dust so you better be in a position to make over 17m in the period of time spent bossing...