The best transfer value to Best Western is from Diners Club Club Rewards. But if you don't already have one of those, you can't get it right now (they're haven't been taking applications for many months).

I can think of no other programs besides Diners Club Club Rewards and Amex Membership Rewards which transfer to Best Western. No hotel programs transfer to any other hotel programs. And very few airlines transfer to any hotel programs any more (mostly to Hilton Honors, not other hotel programs). So I severely doubt there's any airline in the world that transfers to Best Western. And the only hotel partner of Citi's TY points is Hilton HHonors.

(And, btw, Best Western has never been one of Amtrak's transfer partners either.)

So unfortunately, from what you listed, Amex MR seems to be your only transfer option (so no "best" or "worst").

Amex MR transfer to BW 1:1: http://www.membershiprewards.com/cat...sTransfer.aspx

So you would need 20k MR points for 20k BW points.

Of course, given all the devaluations at Delta, what else you gonna use Amex MR points for?