Hi -

I humbly suggest Flying Blue. If you can hit elite status, you can redeem for AF Premiere.

Also, the redemption rates on DL are competitive, and there are also the AF/KL Promo Awards. The only thing you won't get are "Elite Upgrades" ... but if you buy/fly Biz, no biggie. Also, DL's FCM makes getting an UG problematic unless you are DM.