I've sorted through the old threads on this, and come up with quite a few strong contenders that appear to either be no more or have no stock when it comes to decent tops:
Tenn: disappeared. Shame, as they did good stuff
Endura: lots out of stock, some overblown branding / fussy designs in places. Camo can do one. The Raglan jerseys look spot on, however.
Polaris: exactly one style of jersey available
Decathlon: not looking great at the moment for some reason
Any suggestions or magic finds gratefully received!
Little Rider Co, Tigo, depending on their age. TLD do kids stuff as well. 5Ten do kids shoes. What about. MX jerseys? As they do MX kids kit all the way down to tiny squidgy sizes.
Ours wore a lot of Adidas - great wicking tops, same with shorts and 3/4's.
We bought lots second hand.
Polaris and Altura under shorts.
Loads of kids seem to wear this stuff now - https://www.shredxs.com/
Sombrio and Chromag are my "go-to" in Canada for kids stuff. Not cheap mind.
I got my little one some bib shorts from Stolen Goat. They have lasted well.
Shredxs have good stuff.
They'll outgrow it before they wear it out
Seem to recall Altura did kids stuff when ours were little.
Madison.
Tigo, mountain warehouse, trespass.
Sendy in Australia. Although my kids are happy to just wear their normal shorts and shirts.
Little rider, or shred XS is by far the most popular around here. Generally as well (better) made as my stuff. As the wearer's grow, it shifts second hand without being advertised.