My 2 cents:
Use whatever gives you the results you want. I have done more mastering than I want(because budgets aren't what they used to be) and have done it with Ozone, as well as stacking up chains of individual plugins. Its how you reach the end result that matters. Any mastering "suite" can be fine, but Ozone's big advantage(to me) is the Master Assistant. Does it make a "better" master? Maybe, maybe not. Does it do it faster? Absolutely. Now, how do you define "better"?(and here is the missing bit of this discussion). There are 2 things that a "real" mastering pro brings to the table; awesome monitoring(their speakers and listening room usually cost as much as my house) and fresh ears(its really hard to be objective when you've listened to the song 200 times). Assuming you are lacking these 2 things(I know I am), using individual plugins can have you chasing your tail for days, while Ozone's mastering assistant might well get you in a good place quickly(time=money) and if you can let go and trust it, the AI that is at work is not going to be fooled by budget monitors in a poorly treated room(because its not listening to that). I say try the demo and listen to the results on many systems outside of your studio space(that's where all this matters the most)
