You cannot pick it. That's the first thing to know, and it saves a certain amount of money.
Every parent has a story about the expensive, beautifully made toy that was ignored in favour of a muslin, a bath duck, or something that arrived free with a hamper. Attachment isn't a response to quality. It's a response to availability at the right moment.
What actually makes one stick
Some patterns hold, even if none of them guarantee anything.
It was there early and often. Presence beats charm. The thing that's around during feeds and quiet moments has a head start on the thing brought out for occasions.
It's the right size for holding. Small enough to grip and drag about — roughly 20 to 30cm for a baby. A 40cm companion is a lovely floor toy, but it's a lot of animal for someone whose hand is four centimetres across.
It's soft in a specific way. Babies find a texture and stay with it. Knitted cotton, short plush, an attached square of blanket. This is why comforters — a small animal head with a flat blanket body — succeed so often. There's something to grip and something to rub.
It has a face they can read. Simple, stitched, calm. No lights, no sounds. Nothing that performs.
Buy two. Genuinely, buy two.
This is the single most useful thing in this article.
The moment a comfort object matters is the moment it can never be washed at a convenient time, or left in a café, or lost on a train. A duplicate solves a problem that is otherwise unsolvable at eleven o'clock at night.
Rotate them so both smell and feel the same. A pristine spare that has never been used is not a spare — it's an insult, and a fourteen-month-old will tell you so.
When it's for awake time
Comfort objects belong to the awake, supervised part of the day — cuddles, quiet moments, the wind-down before a nap rather than the nap itself. Safe-sleep guidance asks for a bare sleep space, so the favourite gets lifted out before sleep. Most families settle into this quickly, and it doesn't seem to weaken the attachment at all.
As they get older, guidance changes. Follow the current advice for your baby's age where you live.
If you're buying as a gift
Go plain and go early. A simple knitted animal in a quiet colour, given at birth, has a far better chance of becoming the favourite than something elaborate given at one — by then the position is usually filled.
And accept the odds. Most of these don't become the one. It's still the small gift most worth making, because when it does happen, it's the object that ends up in every photograph for four years.