Where are your funds now?
Trading where your assets already sit avoids a bridge entirely, with its fee, its delay and its risk. This usually dominates everything else for amounts that are not large.
If the pair you want has adequate depth there, stop. You have your answer.
Is the pair deep enough for your size?
Check the price impact for your actual amount, not the pair in the abstract. A major pair with millions in depth on one chain can have a few thousand on another, and your order hits a completely different curve.
If price impact exceeds roughly one percent, it is worth comparing another network before continuing.
Depth also changes through the day. A pair that is comfortable during active hours can thin out noticeably when its main participants are offline, and a quote taken at one hour is not a promise about another. Re-quote at the moment you intend to trade.
What does gas cost relative to the trade?
Fixed gas dominates small trades. A swap costing a few dollars of gas is irrelevant on a large trade and crippling on a small one, which is why network choice is effectively a function of size.
For small amounts, any low-fee network beats mainnet by so much that nothing else needs considering.
Where do you want the output?
If the tokens are going to a protocol, an exchange deposit or another wallet, trade on the chain that destination expects. Swapping on a cheap chain and then bridging the output often costs more than swapping where it was needed.
FBT Swap supports BNB Chain, Ethereum, Polygon, Arbitrum, Base, Optimism, Avalanche, Linea, Sonic, Mantle, Berachain, Unichain, Monad, Scroll, zkSync Era, Robinhood Chain and Solana, and shows route, price impact and fee for whichever you select.