Czech is just as difficult as Polish (if not more so for English speakers
For English speakers is the key, and that's why so many people are giving different answers on this thread. What is a hard language for someone English, isn't for other people.
I have no knowledge of Czech, but some words are similar to Polish, Stare Mesto and Stare Miasto for example.
Then there's stuff like Kashubian, which is downright bonkers compared to Polish.
Think I'll just stick to learning one other language.........
Russian
Surely not as hard as Polish, it has one less case to deal with after all ;)
Although getting your head round the alphabet must be hard to start off with :(