Provider comparisons are noisy. Most published rankings blend consumer remittance with private-client property flows, which are meaningfully different products. A short checklist:
Regulator
Look for direct authorisation by a Tier-1 regulator — the FCA in the UK, Banco de España in Spain, FINMA in Switzerland, ASIC in Australia. Agency or introducer models are legitimate but add a layer of counterparty risk.
Safeguarding structure
Segregated client funds held at a Tier-1 bank is the standard to expect. Ask where funds sit while in transit; if the answer is not immediate and specific, that is data.
Published margin
Any provider unwilling to quote a margin range for a transfer of your size, in writing, is optimising against you rather than for you.
Notary-day timing
The provider's ability to guarantee cleared euros in a Spanish account by a specific date is more important than the headline rate.