The best keyword density in the text.

This will be dependant on number of factors. Keyword density will never be fixed but we use in the range of 3% and sometimes as high as 10%
Other factors to take into consideration would be competiton for your keywords and ofcourse quality contextual links and content on your website.
You might want to play around this experiment for a couple of months before taking a decision. But varying keyword density will not bring out drastic variations in serps. Just a couple of positions here and there but again dependant on competition.

 

I simply don't look at keyword density. Just don't overdo it and you will be fine

 

Different people - different thoughts. But in general, everyone agree with 3%. It may be different depending on niche.

@theentry - thanks. Really nice advise. But if your boss asked for that - you should do that )))

 

Of course thats an other situation, but still I really don't check keyword density anymore I just add the keyword in the title, somewhere near the end of the article and 1-2 in the article with a 'b' or 'i' tag, thats all