All of the above. Here's why-they all search custom footprints in different ways.
It will give you a lot better link variety by using several of them. You will get used to what a a lot of these types of blogs look like and also become better at beating out anti spam filters and such.
Use your eyes, brain, and copy and paste when using these free manual commenting programs. This will give you several ways to get a lot of good backlinks quickly.
I started with those and soon learned to follow the trails of other comment spammers by putting their sites into backlink watch.
Copy and past the comment forms and especially the capchas (and hi lite the captcha pics.) Paste them into a text file. You would be suprised at what shows up that you cant see on site.)
These are the common footprints that you can use parts of in quotations for search queries to find more unique blogs to comment on.