Bottom bracket harder to turn half way around
When I turn my cranks with no chain attached, it's pretty smooth, no real noise and just goes for a while if I let it spin.

This does not look like a bad bottom bracket.

When I attach the chain I can turn about half a rotation freely and then it becomes stiff and seems to be in the same place each turn.

However, chain and other attached stuff creates a side load onto the bottom bracket, which may skew the crank axle a bit, and that may reveal looseness in BB's bearings.
Have you tried to wiggle the cranks side to side by hand when they are installed? If you can see or feel noticeable play, then it is a sign of worn bottom bracket.