First off, there's a difference in wanting to be and being. Defining both of them is crucial to achieving the change we want in ourselves.
I think the most crucial point to _Become the best version of ourselves_ is to define clear goals. What do you want to be and what do you want to stop being? We all have certain aspects and characteristics that we don't like about ourselves, heck I do too, but there's also things I like a lot about myself. So, to define clear goals of what we want and what we don't, would be our first step into _Being the definitive best version of ourselves._
Once we've assigned our likes and don't to a sort of "List of Goals", that's where our slow but steady process of changes start. Creating our list of goals is crucial because otherwise we'll end up with a lot of sour moments like "Dang, I didn't like how I reacted to this specific situation" and then not doing anything about it. So, once our set of goals are properly identified, we should start to progress over them slowly; Eliminating or reinforcing certain aspects of us takes time. A lot of time. But it's not impossible; This training of our character could be compared to training our bodies with exercise, or training our metabolysm and digestive system during a diet. It requires time, effort and practice.
So I believe it's safe to believe that we should aspire to become the best version of ourselves to achieve the "Simply being the vest version of ourselves." They're both the same side of a coin. You need a certain process of changes to achieve that goal. Trying to be the best version of yourself with no proper background preparation is like entering a race without even trying to jog in the last 3 weeks.