I prefer to use my favorite, and worlds best, mechanical pencil (Pentel PS535 0.5 mm "Sliding Sleeve Sharp for Pros") for everyday writing, note-taking, etc. I needed some replacement leads, and instead of the normal #2 equivalent leads (HB), I decided to try one step softer (B). I love it! It makes a world of difference. You get a much darker line. You don't have to press as hard. It is easier to write on soft paper, like newsprint, without tearing it.

Two minor minor drawbacks:

1. I go through leads quicker.
2. They can break sometimes while in the storage part of the pencil.

They don't break for me while I am writing, though, because of the sliding sleeve feature of my pencil.

I want to get a couple more mechanical pencils and load them with colored leads. Probably a blue and a red. I wanted to put it on my Amazon wish list, but they don't carry them. This is a link to Office Depot's listing.

The PS315 is basically the same pencil, but with a blue barrel instead of black, it doesn't have the decorative metal band midway down the barrel, and the clip isn't attached quite as elegantly. The PS315 does have grooves that go around the barrel, where as mine does not. This might make it easier to hold onto for extended periods. My pencil is $9, and the PS315 is $8.