I definitely don't like #1 -- way too harsh.
Remember that there are really two sound effects we're going for here: one for the mouse click, and one for the "tab change" sound effect. I think that #5 could be perfect for the tab change one, honestly.
The others are okay, but don't really sound right to me. I'd go with #5 for tab change, and then see if you can do something similar that is a little less sharp for the main click sound that people will hear over and over and over again. I really like how these almost sound like water drops rather than some mechanical thing.
Speaking of which, another sound effect that gets played a lot and which a lot of people really dislike is the item pickup sound effect. I'm thinking that click #4 could actually work well for that. It's a bit abstract, but it's fast and non-piercing and would convey the idea well enough it seems like.
Thoughts?