My gym has these really weird bars - one is tiny, and the other one has a fat grip lining it. Which one would be preferable to use for squatting?
The smaller one is between 4 and 5 feet, and the larger one is almost 6 feet.
I'd find a new gym. But if this is your only option there's pros and cons to both. Without knowing the length I'm not sure which I'd use.
The longer one I would fear would snap in half under tension, but if you're just starting out this might not be a valid concern. I would be cautious putting 300+ lbs on that though... I might be cautious putting 100 lbs on that really. The shorter one will be a bit stronger just due to mechanics.
The problem however is depending on your own body the shorter one might be too narrow to grip comfortably. That depends on your joint health, how big you are, and your flexibility.