Unsurprisingly, there is no one-size-fits-all approach to education. Some kids do better with tracking, some don't.
Focusing solely on objective criteria (that really aren't all that objective anyway) for individuals seems most fair at the individual level, but even if you don't care about anyone else, it ignores that group outcomes affect individuals, too, and that there is more than one kind of learning that takes place at schools. Gifted kids in enriched classes lose out on things, too.
This whole topic always frustrates me, because if we would only devote the kind of resources of money, priority, and support that we should to education, these wouldn't even be issues at all. There would be plenty of choices without taking away from one child, or one group of children, to give to another. It's only because we skimp so much on education that we can't get it right for all kids, gifted/special needs/poor/advantaged/male/female/minority/urban/rural/etc.