If you could learn any language without considering outside factors...

[jeff_lindqvist]

This got me thinking of these threads:
Languages you would learn purely for their beauty
Replace all the languages you are learning with ones that have less than 2 million speakers

[Dragon27]

I'm not sure about beauty, but I would definitely like to learn one of those incorporating polysynthetic languages, like Navajo, just for its grammar. It's a real shame that these kinds of languages are mostly in decline, and don't have much content to offer.

[bpasseri]

I can't honestly imagine choosing a language without the "outside factors" you've listed. Resources that I'll enjoy is high on my list in choosing a language, and culture and where it is spoken is probably second. I have very little interest in language for language's sake.
I've noticed with French that the intrigue really wears off around B2 and it just becomes... A language.. again. Also, I thought I liked the sound of French until A2/B1 And then I decided I honestly hate it but French is a part of my life now and we're not divorcing any more than English and I are divorcing. I suspect every language snores and has morning breath after a while so while I'd love to dabble in basically every language to suss out features and sound, I wouldn't actually want to commit to learning any without those other considerations.

I had the EXACT same experience with French!!! I was completely enamored with it at the beginning stages and all the way through high school. By the time I passed the B2 exam when I was living in Paris it didn't do anything for me anymore and now I feel no real desire to get better at it, I just want to maintain it (mostly because of how much work I put into it). I don't know if anyone else has experience this, but I feel like I have some sort of curse where certain languages sound so mystical when you don't understand them or can only make out a few words, but once you actually get a handle on them the spell breaks and it just feels like another utilitarian way of communicating. I guess that's why they call it wanderlust and not wanderlove!

As for learning any language... there are so many. But if I had to choose one I think it'd be Mohawk. I've never felt so mesmerized by another language before in my life!

[zjones]

Arabic, it's beautiful. I'm drawn toward languages with guttural sounds and flow, hence why I am learning French. Of course, if I was actually going to learn Arabic then I'd probably need to narrow down which dialect I'd like to learn, yikes. Probably Egyptian or Moroccan.

Ukrainian would also be high on my list, although it's nearly impossible for me to separate that language from outside factors.

Swahili. Just like it.

[rdearman]

I already am. Setswana.

[PeterMollenburg]

The comments about French becoming less interesting after reaching B2 or thereabouts and the intrigue of a new interesting language wearing off after learning the language to a certain level makes sense. I think this is very common among language learners, and I’m not immune to it either.

French may not sound less intriguing to me than it used to, but perhaps with the intrigue dropping, the sense of accomplishment and pride that comes with all the hard work I’ve put in (as well as the need to stay up to speed with my children speaking the language) is keeping me involved more intellectually more so to push forward now than attraction to the mysterious sounds...

I think many of us suffer from wanderlust due to the intrigue waning and the desire for a new intriguing language rising.

I’d learn Breton, Frisian, Occitan or Norwegian if outside factors were eliminated. Mind you I still do want to learn bigger languages just because i want to too (not just because of usefulness and so on). And Dutch I’m just itching to ger stuck into.

... English is as boring as bat shit to me most of the time, perhaps because there’s no challenge or intrigue anymore, but boy is it useful!

[aokoye]

I didn't mean to say that one would, or even should, learn solely due to any perceived beauty or due to curiosity of one! As I said even, I have close friends who speak Romanian and I plan to travel there, so if I did end up learning it, these reasons would be largely why. As well, to be honest, I think I meant more of a focus on the intrigue than on the "prettiness," as I think people do on occasion learn languages occasionally for this reason: such as many who study latin simply to gain a better understanding of the origin of the languages which have sprung from it.

With my current group of friends and people I'm around with any frequency who study different languages, most people do focus on intrigue as opposed to "prettiness". Someone asked me what language, among the languages I speak, that I fin the prettiest and I gave him a very quizzical look because that's just now how I categorize languages.

To answer your original question though, if time and energy were no issue I would learn a polysynthetic language.

Edit: and Dutch isn't nearly as mind blowing to me as agglutinative languages are, I do find it both fun and interesting. Yes there will hopefully be some very utilitarian uses for it in my case, but it isn't a "oh this is so pretty," thing.

[lichtrausch]

Without the "outside factors" I would only dabble in languages. I need significant potential usefulness in order to invest serious time in learning something.

[tastyonions]

Unlike many I was never enamored with the sound of French. I just liked the content to which it would grant me access.

With Portuguese, on the other hand, I always loved the way it sounded, and that has not worn off one bit after studying it. :-)

As to the thread question, my answer would have to be Arabic.

[heartlandexpat]

This got me thinking of these threads:
Languages you would learn purely for their beauty
Replace all the languages you are learning with ones that have less than 2 million speakers

Thanks for the redirection, there's some interesting stuff there!

French may not sound less intriguing to me than it used to, but perhaps with the intrigue dropping, the sense of accomplishment and pride that comes with all the hard work I’ve put in (as well as the need to stay up to speed with my children speaking the language) is keeping me involved more intellectually more so to push forward now than attraction to the mysterious sounds...

Oh for sure, even as I grow to like the sound less over time, my interest in learning it certainly has not suffered! With the amount agreeing specifically for french, it feels like it's like a siren that lulls you in with her voice, you realise she's not actually so beautiful, but now you're married and living underwater anyways

I'm also glad for the people saying Arabic now, it was making me sad that there wasn't really middle eastern representation on the thread! I want to say Persian would be on my list as I think that sort of script is so beautiful written, but then clearly I'm choosing for outside influences (I have an Iranian friend) since the written script is actually arabic and doesn't suit persian super well so why else would I not just say Arabic instead? I could make up an excuse and say I found that fact interesting, but I'd be blaggin it and not being honest with y'all haha! I do think it'd be interesting to learn a script language one day though!

Seeing everyone else's answers, I think a native american language would be really interesting too, but I don't know enough to know which. Perhaps Omaha-Ponca solely since that's where I'm from and as much as I hate Nebraska, I'm very sentimental about it! Languages are always very enlightening regarding the culture and general lives of a people, and I think this would certainly ring true for indigenous languages that we learn so little about in school and what we do learn is often pretty incorrect. I definitely think you'd learn a lot learning these languages and would gain so much from it!

With Portuguese, on the other hand, I always loved the way it sounded, and that has not worn off one bit after studying it.

To wrap up a long post, I'm so glad to hear that it's possible!