From Polish perspective Czech language sounds very funny because it very often sounds like diminutive ,funny ,child-like version of Polish. Czech language is in Poland quite popular source for funny t-shirts like with sentence from Star Wars that in Czech version sounds for Poles something like "Luky ,I'm ur dadee" (and I've wrote daddy this way because its even more diminutive than daddy to father). Or there is good standup comedy by one Polish comedian about Pole attacked by Czech rouges.  If you want to watch it you may try to search for "Kabaret Limo Czeski Napad" ,it should work (I use phone now so I cant check it out). So Czech language for Poles is extremely funny but exactly because those two are so similar and we understand each other quite well. But I'm sure it sounds noble for others because it have similar pronunciation  to Polish which I consider the most noble if it gets to pronunciation. I somehow don't like eastern languages though Ukrainian is very good for songs.
Serbian is very beautiful ,and Croatian is in my opinion a mix of rather western pronunciation with some elements of eastern one. When I was listening to one Folk Metal ,Croatian band ,I thought that Croatian language have different words but way of spelling them is perfectly Polish.
btw. There is an album recorded by Polish Folk Metal band Percival (friends of Russian Arkona) called "Slava!" which is a compilation of their versions of Southern Slavic musical pieces. And there are all countries covered from what I recall ,also Macedonia!