First, we're going to take a look at the blue and white (Azorius) Buckle Up deck, which revolves around pilots and vehicles, using the Commander Kotori, Pilot Prodigy to make every vehicle (including a very nice included Parhelion II) easy to crew and effective in combat
Play it on two to avoid Decay
On the play I would almost always have a counterspell that had more potential targets even if it cost two
Sad RobotSad Robot only gets half of its value, as it never dies, and costs so much that you're also unlikely to recast it
It turns the Phoenix matchup into a great matchup and it turns Control from unfavored matchup to a favored matchup
Mythic rares are the splashiest cards in any given set, the ones that generate the most buzz and that usually bring something new to the table, or that enable a special deck built around them