1. This may well be only one of several equally good, but very different universes that God created. Many great artists, writers, composers, have produced numerous outstanding works from which it is difficult to single out one as the BEST. Or this may be the only universe that God chose to make, like some single-book great authors. Who can tell!
Then again, not everything God makes/made may be equally good. After all, even among living creatures, some creatures seem more beautiful and gentle than others. And how can be judge?
Big, big assumption on which hinges the very possibility of answering your question meaningfully. But the assumption may not be correct. I, for one, have no inkling of “all the parameters involved which restrict the design of the universe.” Nor does anyone, I am inclined to think. Under this condition, how can anybody answer the question?
I do not think this is the best, nor not the best, of all conceivable worlds because (as I said) of lack of info on other possible or actual universes. But I do think this is a very good, interesting, and overall enjoyable universe, if only because it has enabled me to become aware of these characteristics. For this, I am thankful to God or whoever/whatever made all this.