Best for mostTom Holland · 2013
Tom Holland's 2014 translation is the one I'd start with — vigorous, witty, genuinely fun to read, which matters in a 600-page book, with Paul Cartledge's notes for context. The most inviting Herodotus for a modern reader. This is where I'd start. (For deep study, pair it with the Landmark.)
Best for going deepAndrea L. Purvis (Landmark) · 2007
The Landmark Herodotus is the reference edition — Andrea Purvis's translation wrapped in maps on nearly every spread, running headers, dates, and scholarly appendices. Unbeatable if you want to never be lost; more apparatus than a casual read needs.