Another vote for the Op 44 polonaise here, I love that piece! (plus I don't care much for Op 22

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One simple thing that's good to know about the polonaise is that the 8th note followed by two 16th notes rhythm that appears everywhere needs to be played as if the 8th note is more like a dotted 8th note, and the 16ths much faster, so the rhythm becomes much sharper than what it actually says in the score.
Also regarding Op 61. It has got a few tricky passages with thirds and some unusual fingerings, but nothing that can't be overcome by good fundamentals and a bit of practice. I would not say it's a huge leap in difficulty over Op 44. Musically, however, it is a very difficult piece. It is very well structured, but can sound like a bunch of randomly improvised elements thrown together, if the pianist doesn't understand their character and purpose in the overall form and cannot hold them together in a convincing and emotionally touching narrative.