What development stacks do the top web3 applications use these days? If a dev was starting a project from scratch, what would you recommend for a well-supported and scaleable framework?
Smart contract development and testing
Truffle and Ganache?
openzeppelin-test-environment?
Remix IDE?
You could look at npm downloads as an indication or stars for repositories.
Truffle and Hardhat are the most popular. I would suggest having a look at Hardhat and then deciding between the two.
I use Infura and Alchemy. Depending on your app you may need to use both to ensure availability.
I don't do much, if any front end. ethers.js is popular, though I have a harder time finding the right documentation when I need it.
Upgradeable using OpenZeppelin Upgrades Plugins, except for simple contracts (e.g. fixed supply ERC20).
Goerli as it is a multi client testnet.
Though it depends on your use case. For NFTs, OpenSea supports Rinkeby. If you have a dependency on another project then you may need to use their preferred testnet.
Prior to deploying to production I would do manual tests on Ropsten (only proof of work testnet).
