As for what SoftStart to use, the factory option was not available in 2021 and I don't think there were clones available for the MicroAir at that time either. So my only experience is with Microair. Being satisfied with Microair, I have stuck with them for the few that I have installed for family and friends.
As long as any SoftStart matches Microair's reduction is starting inrush current surge, it should not matter who supplied it. I know it is a bit difficult to measure the starting inrush current surge, but I would like to see some valid performance comparisons between the various softstarts that are now available. For myself, I would select the one that does the best job, if I knew which one that was.