focus plus, it's their most recent model.
performance wise, the focus and focus plus is quite similar.
focus is semi mod, focus+ is full modular.
bronze one is not recommended as it's a older unit, running two 12V rails @ 24A each. even though this unit has a higher output, if you run a really powerful card, you might run into issue as you can only safely draw 288W from a single rail (unless you uses two rail on the same card) but you might run into other issues as the rail voltage can be different.