Hi, I'm new to bitcointalk.
I'm only 15 years old and I'm Brazilian, I want to know which is the best long-term investment.
for the next bitcoin halving

I'd appreciate you at that young age you already have an interest in the crypto investment and apparently a good time to start either.
The next halving will commence this coming 2024, it wasn't long to wait, right?
https://www.coinwarz.com/mining/bitcoin/halvingTo buy good projects seems to be the best deal in the current situation. Bitcoin of course is one at the top of my list, however, considering potential altcoins is also a great idea. I think you need to start filling your bags now.
I believe OP was lucky to enter the market when there was blood in the market but him asking for the best investment is not enough to make him make a profitable investment in crypto because I believe he needs to understand the market first, how to select right investment and how to secure his investment.
Yes, Bitcoin should be the top priority of every crypto investor especially now that it has gained the attention of institutional investors.
This is the real countdown to the next halving