How problematic is it to choose between “tú” and “vos”? I think it is much more insignificant than it is generally thought to be:
Firstly, because there are formal differences in only two tenses: Indicative present and imperative mood -also in subjunctive present but it is less usual-; and lastly, because no matter which form you choose, it does not represent a problem understanding or being understood by other Spanish speakers from other countries.
Which are these differences?
Vos: No irregularities, stress on the last syllable, change in the ending of “ir” verbs. There is only one irregular verb in the “vos” form for the present tense: SER. IR is also irregular but it’s exactly like “tú”.
Imperative mood (affirmative):
Vos: No irregularities, stress on the last syllable, change in the ending of “ir” verbs. There is only one irregular verb in the “vos” form for the imperative tense: IR
So, if you consider the whole scene, it is not a big deal at all. Who would I suggest to learn one form and who, the other one? I would encourage people on vacation to learn or use “tú” conjugation, especially the ones who have already learnt it and who are staying here for little time and/or only for tourism; whereas, I would totally recommend “vos” forms to the following people:
* Tango lovers (Tango would not exist without “vos” and viceversa).
* The ones who move to BA for work or studies.
* Or simply too lazy students (“vos” is way more regular than “tú”).