The best option depends on whether you need instant access, are saving for a fixed period, and whether your interest could exceed your Personal Savings Allowance. A cash ISA pays interest tax-free, while an ordinary savings account may offer a higher rate but interest can be taxable depending on your circumstances. Compare the annual equivalent rate, access rules, minimum deposit, withdrawal penalties and whether the provider is FCA-authorised. Check current ISA rules and allowances on GOV.UK, and consider comparing accounts through a reputable, regulated service.