I started out with NW, LH, CO, and AC (no strategy really, mostly signed up because I happened to take one of their flights). Made elite in AC but switched to UA in 2000 because UA was employer preferred airline. Matched to AA, DL, AS at various times but ultimately decided to stay with UA because of better redemption possibilities and *A partnership airlines like LH, TG, AC, etc. which better fit my travel patterns.

Disappointed with the new UA but I'm not traveling much these days for business, so having 1MM status is liberating and works out well for personal travel. When UA is competitive price wise, Im happy sending my $$ to Smisek, otherwise I just travel LH, AC, AS, HA, DL or whoever offers the best option.