I agree. It depends on what you want to do. I've been challenged technically at 2 person startups and 100k person companies.

Advice for OP: what companies do you admire? Either globally or locally? Have conversations with folks at that company (LinkedIn is your friend in accomplishing this) and see what people actually working at these companies think about challenges and accomplishments at their employer.

This is an interesting idea.

The parent meant to communicate "big fish in small pond" but tossed in the word company instead of pond. Ignore that bit.

Big fish in small pond still describes the need for room to grow accurately enough.