IMHO, The cryptocurrency "Hex" has the best inflationary mechanism.

First side note, Proof-of-work isn't dead, but it should be. Proof-of-stake is vastly superior (return isn't based on how much electricity you burn, but by putting up risked collateral and running that)

So, Hex. You stake/invest/lock up your coins for a fixed period of time, and the system gives you more back at the end of the term at a fixed percentage; like how so many financial products are supposed to work.

And even better, all "penalties" (e.g. you end stake too early or late) go back to the "on-time" stakers as a bonus.

(yeah, the founders a weirdo but what can you do)