Strong tenant protection: a main-home lease effectively runs up to 5 years (private landlord) or 7 years (company) even if the paper says 12 months
Low deposit: the legal fianza is capped at 1 month's rent, with any extra guarantee limited to 2 more months
Public SNS care is high-quality and free at point of use for entitled residents, with no co-payments except for a share of prescription medicine costs
EU/EEA/Switzerland visitors can use an EHIC for medically necessary public care on temporary stays at no charge, on the same terms as locals

Watch out for

Empadronamiento is mandatory and is the gateway to healthcare, NIE/residency and school enrollment, so register at the Ayuntamiento as soon as you have an address (you typically need ID plus a rental contract or recent utility bill)
Online rental scams (fake listings, requests to wire a deposit before viewing) are common on portals; never pay before seeing the property and signing a contract
A newly-arrived nomad cannot readily join the public SNS: the 'convenio especial' paid scheme requires at least one continuous year of effective prior residence (in Spain or another EU/EEA/Swiss/UK country) plus registration in a Spanish municipality
Non-EU nationals cannot use an EHIC; without it you may have to pay upfront and seek reimbursement later

Cost of living

Barcelona

€1,950–€2,750/mo