This one. I also read Code Complete (2nd ed) when I was a junior and found it very helpful, but I don't know how well it has aged. Object Design by Wirfs-Brock

This one. I also read Code Complete (2nd ed) when I was a junior and found it very helpful, but I don't know how well it has aged. Object Design by Wirfs-Brock is a practical OOP book. I would avoid anything with clean code in its name, they're generally dogmatic and obsessive about TDD.