Thanks folks for your responses so far.

The thing that's weighing in favour of MH, though, is that only their elites get additional *pieces* of luggage (on top of extra kilos) on MH. And I'm likely to do more of my leisure travel with MH, where the more bags/kilos I can carry, the better.

Of course, there's also the question whether I would ever reach top tier on Enrich anyway. If my clients switch away from SQ, as they are appearing to do, I would try first to retain at least *A Gold (probably on SQ/KF), then work on getting OW Emerald (on whichever programme I finally decide upon).

Given my current travel patterns it would appear that one of the non-expiring programmes like AA's would fit best.

Am I missing anything?