Bank Rewards/Transferable loyalty programs
Ultimate Rewards (as of June 2022):
All are transferred at a 1:1 rate. Ultimate Rewards are so easy to earn (thanks to bonus categories and shopping portals).
Amex MR (as of June 2022)
Most Amex partners are 1:1 but there are three exceptions. American Express Membership Rewards points transfer to El Al at a 1000:20 ratio, JetBlue is a 250:200 ratio, and AeroMexico is a 1:1.6 ratio.