I have the 18-50 f2.8 as "standard" lens and I'm very happy with it.
I don't do any "tests" nor do I read them as real life is never laboratory conditions.

Important points for me are, apart from the fact that the quality is very good:

• when zooming, the lens does not rotate. This is handy when using some filters. The lens does become longer though.
  When focusing, it does not. Autofocus works fine with it (2.8 throughout) and manual is also ok.
• the front lens is really at the front. Meaning that it may be a good idea to protect it with a skylight or uv filter. Or use the sun hood.
• 18 corresponds with appr. 29mm, which makes an acceptable wide-angle and 50 corresponds with 80mm, making it ok for portraits etc.
• I also like it because when you want to go more wide-angle, it fits nicely with the 10-20, and, at the other side, you can go the 105mm way ( close-up to 1:1 and an acceptable tele, coor. of some 170mm), 150 (even better) or, of you're into animals, up to a 300 or more. Or add a zoom like the 70-200 f 2.8.

It always fits nicely in the middle of everything, allowing expansion and making it a very good standard lens.
If you want to, and you have about a week or so of patience, I can send you somefull-size shots that are taken with it.

There are no Borg. All resistance is fertile.