Honest answer, mate: nothing in the cheaper brands gets you a clean swap for Little Greene Hicks' Blue. It's a punchy, saturated mid-blue with a lot of character, and the nearest matches we've measured all drift off enough to read as a different colour in the can.
The closest is Dulux Azure Fusion 1 (LRV 5.4) at ΔE 8.7 from the original. To put that in context — anything under ΔE 2.5 is what we'd call very close, and under 1 is imperceptible. At 8.7 you're well into "that's a different blue" territory. It's in the same family, but side by side you'd see the shift.
The other contenders are further still: Crown Midnight Navy (LRV 6.6) lands at ΔE 12.9, and COAT David Rose (LRV 4.1) at ΔE 11.4. Both are darker and more navy-leaning than Hicks' Blue — useful colours in their own right, but not stand-ins for this one.
So here's my steer. If you genuinely love Hicks' Blue specifically — that bright, almost gemstone quality — buy the Little Greene tin and be done with it. On a feature wall or a few metres of joinery the price difference is small in real terms, and you won't spend the next two years squinting at a near-miss wishing you'd just bought the original.
If the budget is firm and you're open to *a* good blue rather than *this* blue, COAT David Rose is the one I'd look at — strong pigment, sound trade-quality paint, and a sensible price. Just go in knowing it's its own colour, not a dupe.
Whatever you land on, order a peel-and-stick sample or brush out a test patch and live with it across a full day. Deep blues shift hard between grey morning light and warm evening light, and that swing matters far more than a few quid on the tin.