Crocheting / knitting amigurumi with cotton or acrylic yarn: which is better?

Dear community,
which material do you prefer for amigurumi?

Definitely cotton.

Cotton, because acrylic tends to stretch when crocheted tightly and is prone to forming holes.

I like acrylic yarn best because it washes well—even in the washing machine—which is definitely a must for amigurumi meant for kids ;-). I also sometimes use sock yarn when a friend brings me her leftover yarn—either because she has extra or just wants to get rid of it. And since I don’t knit socks, I just put it to use in other projects.

Definitely cotton—acrylic yarn stretches too much, and the figures don’t look as nice then.

Cotton, definitely. If you work with a smaller hook, they turn out really firm, have no holes, and are incredibly durable. For example, the cotton balls with a rattle inside have been regularly torn to shreds by my cat for years; they’ve also been in a small dog’s mouth and in the washing machine several times, and they still look almost brand-new. The big tractor—which I made using a pattern from here and thick acrylic yarn—looks more than just worn after not even a year, even though it’s always been treated well and has never had to be washed...

Definitely a plus for cotton yarn. That's all I crochet with.

I’ve worked with both. Acrylic yarn worked well, too—I crocheted it tightly, and there was no difference from cotton. However, if it’s going to be used by a child, I’d only use cotton, since acrylic does shed a bit, and loose fibers can be dangerous. If the amigurumi is just for decoration, acrylic works fine, but you have to work with it tightly. And the acrylic yarn needs to have a smooth texture. 

I just thought of something else. I’ve also used blended yarn before—I especially like the Turkish Alize brand. It’s wonderful: it looks like cotton, is sturdy, but is softer thanks to the acrylic content.
And it’s cheaper than most cotton yarns. 

Definitely cotton! It’s more expensive, but I don’t like acrylic at all: too smooth, too slippery, and often too bright in color.