Wickham Gray is a lovely cool, airy off-white with the faintest green-grey lean — that soft, almost-not-there quality that makes it sit so well in light-filled rooms. Benjamin Moore isn't the priciest paint out there, but if you're doing a whole house it adds up fast, and the good news is the match here is genuinely close.
The pick of the bunch is Crown Willow Breeze at ΔE 1.5 (LRV 65.9). Anything under 2.5 is very close and under 1 is imperceptible, so at 1.5 you're well inside "the eye won't clock the difference" territory. Crown's trade availability and price point make it a sensible swap for a large job.
Right behind it sit two more, both at ΔE 1.6: Dulux Clouded Pearl 1 (LRV 69.3) and COAT Rathbone Place (LRV 69.5). The Dulux is a touch lighter and slightly cooler — handy if your room is a bit gloomy and you want to push the brightness. COAT is worth a serious look if you care about low-VOC, water-based credentials; they're a younger British brand doing properly modern paint, and Rathbone Place lands almost exactly where Wickham Gray does.
The "but what about" here is undertone behaviour. Cool greys with a green lean like this one can go a little flat or even faintly cold in a north-facing room. All three matches share that same DNA, so they'll behave the same way Wickham Gray does — which is the point, but don't expect a cheaper tin to magically warm up a chilly room. If yours faces north, test before you commit.
My advice: get sample pots of Willow Breeze and Rathbone Place, paint two coats on A3 card, and move them round the room across a full day. At these ΔE figures the colour decision is basically made — you're really just choosing on finish quality, sheen and price.