I like your question. It's well thought out and examining different dubs is a great way to juxtapose the languages, All in all I agree that it depends on the person, as voice and intonation have a lot to do with the 'beauty' of the language and that all languages are beautiful in a way, having unique elements which set them apart.
That being said I'll just give my opinion so I'm sorry if it offends anyone.
* English: Yes for me English is by far the most beautiful language by far. It's just so perfect - I really love hearing and speaking it (It's my third language) cuz it flows so naturally, and the wide array of British accents is amazing!! I just love it in every way and I think it sounds great.
* French - Studied French for 3 years (I'm one of those people who gets the accent thingy too :P) and I have to say I don't really like it - I just don't find the sound appealing. Still I think it's a wonderful romance language which is easily likable and enjoyable, just not up my alley.
* Spanish - Sounds amazing. My sister is fluent in both Spanish and Portuguese and it's probably the second language I'd watch movies in after English (maybe cause I was watching Spanish TV as a kid).
* German - My father is fluent in German and thinks it's a beautiful language... and I'd have to agree 100%. Many people think it's harsh and angry but this is seriously wierd to me.. I love German but find that Latin (romance languages) sounds much better.
* Russian - Speak fluently. My first language although I'm not a native. Sadly my experience with Russian people and the language have been pretty unenviable so I have mixed feelings about it... However it's an amazing language in itself, very beautiful Slavic elements - but can definitely sound harsh and unpleasant more than any other language on this list I'd say.
* Japanese. Love it. I study it currently and this language is just fantastic!! I guess any anime fan would find her enamouring but it's really すごい!My second favourite language.
* Chinese - I'm not familiar with the language although my cousin graduated in Chinese so I didn't form any substantial opinion. It's pretty good though, judging by the video.
* Hebrew - I'm a native speaker and this is the only 'Eastern' language here. I live in Israel so I can honestly say I REALLY dislike this language. Bu then again I dislike middle eastern languages and cultures in general so this clearly won't be an exception. I think when spoken by Israelis it comes off even more horribly (sorry if I offend anyone) so yeah... I'd stick with European and Far Eastern languages. One of the things which bugs me most is that it really doesn't flow like English and Japanese and I have to exert myself to produce any distinguishable sounds at all. Probably just me though...
For me it's English hands down but every language can be beautiful of course :DD