Haven't dined at Joso's, but they are known for their calamari, grilled fish and squid ink risotto. http://chowhound.chow.com/topics/753066
I would expect Zee Grill offers more bang for the buck. Zee Grill offers more innovative seafood dishes drawing on inspiration from different cuisines, whereas Joso's offers fairly traditional Croatian/Mediterranean-style seafood.
Atmosphere-wise, Zee Grill seems somewhat cluttered and cozy to me. I really like the desserts I've tried at Zee Grill.
I'd be more likely to dine at Zee Grill, mostly because I tend to prefer innovative approaches to seafood, rather than more traditional Mediterranean approaches, when I'm dining out.
202 Davenport Rd, Toronto, ON M5R1J2, CA
641 Mt Pleasant Rd, Toronto, ON M4S, CA