The best way to decide is to make a trip and see it with your own eyes. Both places are awesome and the people is great , but it depends what yo like more.
If you come to Argentina, check www.tourslatam.com and you'll see some good activities to do.
Cheers,
Fran
Brazil
In my opinion, Brazil has better beaches, it is cheaper to live in Argenitna both have nice people but Brazilians are a warmer but the scenery is prettier in Argentin--Brazil is pretty too but the distances are huge.
As far as
1-Beaches
2-Living there
3-Nice people?
4-Is it pretty there
Which one would be best please give a very detailed answer and I speak English,Portuguese, and French just thought that might be helpful or useful information thank you