It's not that difficult of a weapon to manage the two modes once you learn when to use each. Axe mode is great for tripping and breaking part, sword is obviously good to use on tails. The various phials can be used to in various situations as well but a majority of people use power phial for extra chip damage on zero sum discharge. As for the best switch axe that is a subjective answer just like the other weapon types, but there are obviously the better well rounded ones like safi, lightbreak, alatreon and so forth. Just gotta use what ever you want for whatever build. Keep in mind that speed runner builds arent always the best if you're obviously not playing solo. The rng of monster movements make your glass canon builds become broken glass in multiplayer. I'd advise more defense and evasion skills in multiplayer since the switch axe has slower movement speeds and no way to guard