learning languages in a logical order

[tiia]

Taking the Finnish alphabetical order, it would be Spanish first, then French and German at last. (Because it's espanja, ranska and saksa)

I think the dice method mentioned by Iversen is a good one to find out whether there might be preferences towards one of these languages. Otherwise, if the prospective student is an English native speaker, has not yet learned any language and really has absolutely no preference towards any of the three, I'd start with Spanish and then either French or German. Maybe German before French to make it easier to keep them separated.

But why Spanish first? Because Spanish doesn't have cases. It's quite complex regarding the tenses, but it's in my opinion easier to avoid using complex tenses in Spanish than the cases in German. Despite this, tenses in general are known to an English speaking person, but a learner might not (yet) be so conscious about cases.
The other reason for putting Spanish first, would be that the phonology is pretty straight. It follows the "each letter has usually only one sound"-principle the most out of the three languages. There are much fewer silent letters than in French. This helps also for learning e.g, the German pronounciation, because then only the German specific rules need to be learned.
But maybe that's just me and it would work out the same way from German to learn the Spanish specific pronounciation rules.

[Chupito]

Another option would be to take some time to dabble in each and explore the cultures/countries associated with each for a moment - maybe for a week each, maybe for a couple months - or just begin all three and see if you develop a preference or if one naturally falls behind. Say you decide to look into Spanish this week and the next on French and when it's French's turn, you keep wanting to go spend more time with Spanish. If you have the same level of interest for all, it might be that you don't know or care much about any. Getting to know them better could help.

[Cavesa]

I'd recommend starting with the one you would regret not having learnt the most.

Life is complicated, free time may disappear. It is nice to have plans for several languages, but who knows at what point are you gonna get stuck (like me).

So, I'd recommend imagining the moment you need to take a break from the plans. Which one would you prefer to get stuck with for months or years, before being able to continue your journey to the others? Which one would would bring the most regrets like "I wish I had learnt x, while I had the chance"?

That is the most logical order, in my opinion. It is based on your needs and preferences and on the real life. There is no universal logical order for these three, you will find people taking all of the combinations and being happy about the choice.

[tarvos]

For a language learner that has the goal of learning multiple languages, is there any reason to learn those languages in a particular order?

For example, let's say that someone wants to learn Spanish, French, and German, but that person has the same level of interest in all three languages. Would there be any benefit in studying any one of those languages first?

Doesn't really matter. I went French, German, Spanish, in that order, but that was because I was taught the first two at school. Honestly it doesn't hugely matter which one comes first. Pick one and go for it!

[garyb]

If I could go back, I'd think a little less long-term and more about how useful each language is in the short to medium term. I decided to do French then Italian then Spanish because it seemed sensible and logical to stick to the one I had already started and take that to a high level before moving onto another, even though I had quite a few Spanish and Italian-speaking friends at the time. I suppose my mistake was thinking that things would stay the same in the future, or that learning French would somehow in itself create more opportunities to use it.

What happened is that I spent a few years on getting good at a language that was useless to me and trying make it less useless by using it in artificial contexts like language exchanges and meetups with far more learners than native speakers, and by the time I finally moved onto Spanish I no longer had friends who spoke it and the Spanish-speaking community in my city has diminished considerably.

Of course learning a language is a long-term commitment and it'll take a while before your hard work results in a useful level, and learning several at a low level isn't very productive, so I'm not saying to only consider the short-term opportunities or to chop and change based on them. But there's a balance.

[javier_getafe]

If I could go back, I'd think a little less long-term and more about how useful each language is in the short to medium term. I decided to do French then Italian then Spanish because it seemed sensible and logical to stick to the one I had already started and take that to a high level before moving onto another, even though I had quite a few Spanish and Italian-speaking friends at the time. I suppose my mistake was thinking that things would stay the same in the future, or that learning French would somehow in itself create more opportunities to use it.

What happened is that I spent a few years on getting good at a language that was useless to me and trying make it less useless by using it in artificial contexts like language exchanges and meetups with far more learners than native speakers, and by the time I finally moved onto Spanish I no longer had friends who spoke it and the Spanish-speaking community in my city has diminished considerably.

Of course learning a language is a long-term commitment and it'll take a while before your hard work results in a useful level, and learning several at a low level isn't very productive, so I'm not saying to only consider the short-term opportunities or to chop and change based on them. But there's a balance.

As I would said in español: "Amén".
+1

[Jean-Luc]

Best "learning language logical orders" are the opportunities arising to speak the languages...
Being goal oriented (a job, travel, a friend on line...) or following your desire are too, in my opinion, more important than any "order". And there are so many languages!