Honestly, you can't go wrong with either — these are two of the best paint brands money can buy, and both are made in Britain. The choice comes down to what you value.
Farrow & Ball is the bigger library — 301 colours against Mylands' 211 — and it's the one everyone knows. Its real strength is greens (67 of them) and blues (41), and the colours have that famous chalky, light-shifting depth that changes through the day. If you want a colour that's been pored over by half the design world, F&B delivers. Their LRV range runs 5–92, so you've got everything from inky and dramatic to barely-there off-whites like All White, a clean, uncomplicated white that's a genuine workhorse. Acid Drop shows the other end — a punchy, zingy green-yellow that proves the range isn't all muted neutrals.
Mylands is the quieter connoisseur's choice, and its trump card is durability. The Marble Matt finish is noticeably tougher and more scrubbable than F&B's Estate Emulsion, which matters in hallways, kitchens and anywhere with kids or dogs. And it can do deep and theatrical with the best of them — it's a paint with real film and theatre set heritage behind it. Look at Market Green No.38, a smoky, deep blue-green, or Empire Violet No.80, a moody aubergine-violet with proper drama. The pale end is just as well judged: Acanthus Leaf No.12 is an easy off-white and Alderman No.60 a light, warm putty-beige, and their neutrals (40) and whites (25) are quietly brilliant.
The "but what about" question is usually price and coverage. They're priced similarly — both premium — but Mylands often covers in two coats where F&B's deeper colours can need three, which closes the cost gap.
My honest steer: if you're painting a feature room or want a specific iconic colour, go F&B. If you want a hard-wearing finish in a high-traffic space, or you fancy something a bit less ubiquitous, Mylands is the smarter buy. Get tester pots of both, give them two coats on big boards you can move about, and judge them in your own light — that's the only test that counts.