No, they can't -- and anyone who thinks they can is talking out of a bodily orifice other than their mouth. The best "blog script" (blogging platform) depends on the nature of the blog, and the site that's built around the blog (or that the blog is integrated into).
A lot of people might want to say "
WordPress!!!" out of reflex, but WordPress left the humble blog behind a few versions ago and has become a pretty sophisticated CMS (Content Management System). Yes, there are a billion and twenty-three templates (free and otherwise) available for WordPress, but if all you want is a simple blog, or if you want to integrate a blog into an already-existing web site, then WP may be way overkill. There are a lot of features in WordPress, and a lot of complexity -- and (although the new version,
"Gershwin", is much better in this regard) it's a performance hog. Still, it does what it says on the tin, and if it's what you need it's a decent enough choice.
If the "blogging platform" is really meant to be the foundation stone for a much larger site (of which the blog will only be part) then a full-featured CMS like
Joomla or
TangoCMS might be in order. (That's far from an exhaustive list; I've just picked a couple of representative samples.) It can be a bewildering ordeal for a novice to turn a full-featured CMS into "just a blog", but if your site needs to be much more than "just a blog", then you'll want to have as many of the core features you need in one box as possible.
If you're running a high-traffic blog (millions of hits per month) then you'd probably want to give some serious consideration to
Movable Type. It's not free for most purposes (you can get a free version in the dev channel, but the usage restrictions are pretty heavy), but it has one
huge advantage over most blogging platforms: it creates static pages that can be served with the absolute minimum of server activity. Almost every other blogging platform out there hits the database every time a page is opened; Moveable Type just returns the requested plain-vanilla HTML page. The only real processing hit comes when you publish a blog entry or when comments are submitted (or approved, if you're moderating comments), everything else could be done by a rickety old 386 and still face more traffic than most bloggers would ever see.
At the other end of the scale are lightweight blogging engines like
Chyrp. It does one thing and one thing only: it lets you blog. You can customise the appearance of your page using CSS until the cows come home, so it doesn't have to be ugly, but it will never be anything much more than a blog. It doesn't pretend to be, and it doesn't try to be. I've even seen a complete blogging engine that consists entirely of a single small PHP file (less than 5KB) that hooks to a MySQL database (though I can't remember the name offhand).
Then there's the editing environment to consider. How much formatting of text do you want to do? Are you conversant with HTML? How about Markdown or LaTeX? Do you prefer a distraction-free writing environment, or do you need to have formatting and editing tools available all of the time? Do you need to be able to upload graphics and have the platform take care of the details for you, or do you prefer to optimize the thumbnail/inline and display images in a separate graphics/photo editor and
not have your blogging engine mangle things?
But if all you want is a blog, why worry about the engine? There are plenty of hosted alternatives out there, like WordPress.com, Blogspot and Tumblr that are more-or-less "sign up and go". They'll all work for a blog, and if it does what you need in the way you're most comfortable working, then for you it's "the best".