Tether already put USDT on the ERC-20 ethereum blockchain. But the ERC-20 version is rarely used anyways by exchanges so it doesn't even matter. The vast majority of USDT deposited on exchanges is the OMNI Protocol version (BTC). The Tron version will probably suffer the same fate.
Bitfinex (and by extension Tether) is a scam. I prefer USDC as a stablecoin because it's owned by more reputable American exchanges (Coinbase and Circle). And the ERC-20 protocol allows you to store your USD on hardware wallets. Though PAX and TUSD are more popular (higher trade volume) and also part of the ERC-20 standard.
DAI is my guilty pleasure, only crypto based project i've looked at and seen a iota of tangible real time real world value, though realistically USDC is probably the best alternative for now, stability wise.