If you are equally strong in Python and JavaScript, Brownie is a better choice, because Python as a programming language is more suited for tasks needed from a smart contract programming framework.
You can handle numbers, like uint256 and decimals, as numbers in Python whereas in JavaScript you need use strings or hacky classes. There are a lot of big numbers in smart contract development.
JavaScript forced async/await makes linear code, like a deployer, harder to follow and read, whereas in Python threaded model and optional async keeps simple scripts simple to debug
Python is natively optionally typed whereas in JavaScript you need to transpile to TypeScript, decreasing debuggability and bringing other issues as well
Pytest testing framework makes tests faster and easier to write and read. Tests are a crucial part of smart contract development and making testing easy is critical for security.
Python is the number one language in data science and finance, so there are many other synergies to financially related blockchain work.
JavaScript is used in-browser and all web frontends. If you need to learn programming languages from the scratch, in some point you need to write a frontend for your smart contract and JavaScript programming knowledge will become necessary.
An example comparing the readability of a single line of test code between Brownie and Truffle
assert(await staking.methods().currentlyStaked.call()).toNumber()).equal(STAKE_PRICE + STAKE_PRICE_2);
Would be in Python:
assert staking.currentlyStaked() == STAKE_PRICE + STAKE_PRICE_2
Also if you need to stick with JavaScript (you do not know Python) I suggest going to Hardhat instead of Truffle. Hardhat is a newer, more modern, JavaScript-based smart contract development framework and easier to work with than Truffle that carries a lot of legacy code.