The first criterion that matters is the one most people misread: crypto exchange maker taker fees. Kraken Pro's published spot schedule starts at 0.25% maker and 0.40% taker at the lowest tier, and steps down with 30-day volume; for very high volume on select lower-liquidity pairs, the maker side can even go negative (a rebate) down to -0.02%.
Coinbase Exchange also publishes a clear tier ladder, but its entry tier is costlier: 0.40% maker and 0.60% taker up to $10K in trailing 30-day volume. Binance.US is the outlier—on Tier 0 pairs it advertises 0% maker and 0.01% taker regardless of volume, which is hard to ignore if your trading fits inside that product box.
Gemini ActiveTrader is the toughest pill for fee-sensitive newcomers: its base spot tier is 0.60% maker and 1.20% taker, only becoming more palatable as you climb tiers or when you're trading the specific stablecoin pairs that price at 0.00% / 0.00%.
Second, don't treat free deposits as the end of the story. The real cost is often time-to-withdraw and wire pricing—this is where crypto exchange deposit withdrawal fees become decision-shaping. Kraken's USD ACH (via Plaid) deposits are free and near-instant for trading, but they come with a 7-day withdrawal hold.
If you need clean, hold-free funding, Kraken also supports USD FedWire deposits with no fee and typically fast crediting, and its USD FedWire withdrawals cost $4. Coinbase Exchange keeps ACH simple (free in and out), but wires are meaningfully priced: $10 for a USD wire deposit and $25 for a USD wire withdrawal.
Gemini's fiat rails are straightforward on paper—ACH deposits and withdrawals are free, while USD wire withdrawals are $25—and it also lists card and PayPal funding costs (3.49% debit card, 2.50% PayPal), which I consider emergency convenience, not a default plan.
Third is the fee you can't pre-quote with a single percentage: withdrawals to your own wallet. Gemini explicitly uses dynamic crypto withdrawal fees designed to track current network conditions and shows the amount before you initiate the withdrawal. Binance.US similarly states crypto deposits are free, but withdrawals use a dynamic fee model and the amount can change from transaction to transaction.
You should treat the preview screen as the source of truth. Kraken and Coinbase also vary by asset for crypto withdrawals, so the practical rule is the same across all four platforms: do a $10 test withdrawal first, confirm address hygiene, then scale.