Bartok, which may have to do with the fact that his music just became public domain in 2016.
Moszkowski!To be honest I don't know too much of his output, but what I have heard is great and deserves more attention. Horowitz popularized a few of his etudes and Etincelles Op. 39 No. 6 as an encore but I've hardly heard of his music otherwise.
Woelfl. Spent a most joyous week on his sonatas.
Szymanowski - I quite like his Nocturne and Tarantella for violin and piano, and I remember hearing some other piece for violin and piano that I quite liked but don't remember the name of. I remember trying to get into some of his piano music a few years ago but it didn't click. Do you have any good tips on pieces by him?
I'll also nominate Isaac Albéniz. Iberia is probably his most famous work, but there are many others.
Man, you guys just keep delivering the goods I will listen through it all at work tomorrow, maybe there is something new in there that I'll want to learn... Happy to see that someone else likes Pöntinen!