ATOI

The main goal we wanted to achieve by writing this plugin was delicate tags appearance tweaking. Now plugin supports tag color and size tweaking, pretty urls, automatic and manual tags and tag cloud output, tag preview and tagged posts count. Such features as tag aliases and search by tag are planned to be implemented in next release.
We are glad to introduce this plugin to the community. If you think that it is necessary and there is need in developing it further, we will do it.
Bug reports and feature requests are welcome.
<h3>Example</h3>
There are 100 posts with tags as your site. 
There are four tags defined: tag1, tag2, tag3, tag4. 
Tag1 has 10 posts, tag2 has 40 posts, tag3 has 20 posts, tag4 has 70 posts (post can have more than one tag). 
There are 3 colors (color1, color2, color3) and 2 sizes defined (10px, 30px). 
So there are 3 color categories and 2 size categories. 
If a tag has less than 33% of tagged posts, it gets into 1st color category. 
If it has more than 33% and less than 66% of tagged posts, in gets into 2nd color category. 
If it has more than 66% of tagged posts, it gets into 3rd color category. 
The same thing with colors. 
So: 
tag1 – 10 posts (10%); color:color1; size:10px; 
tag2 – 40 posts (40%); color:color2; size:10px; 
tag3 – 20 posts (20%); color:color1; size:10px; 
tag4 – 70 posts (70%); color:color3; size:30px;

Xata33 Tag

The main goal we wanted to achieve by writing this plugin was delicate tags appearance tweaking

The Krotek

Customizable widget and shortcode to display tag cloud anywhere you want. You can use it as standard tag cloud widget, as shortcode in any post or page, or both ways. Tons of options allow you to fine tune cloud layout to your needs.
STANDARD FEATURES
<ul>
<li>Display list of post, category or link category tags.</li>
<li>Define number of tags to be displayed.</li>
<li>Set custom tag separator.</li>
<li>Select tag taxonomy: posts, categories or link categories.</li>
<li>Choose cloud mode: shortcode only, widget only or both.</li>
</ul>
PREMIUM FEATURES
<ul>
<li>Define smallest and largest tag size.</li>
<li>Select size unit: px, pt, em or percent.</li>
<li>Choose layout: standard flat cloud or unordered list.</li>
<li>Order tags by name or count.</li>
<li>Sort tags ascending, descending or randomize.</li>
<li>Define list of tags to exclude from cloud or include only.</li>
</ul>
You can purchase Premium version <a href="https://thekrotek.com/wordpress-extensions/tag-cloud" rel="nofollow ugc">here</a>.

Custom Tag Cloud

...but it at least is a little better than the one that comes with WordPress.

Free version is not very customizable...

Customizable widget and shortcode to display tag cloud anywhere you want.

Xata33 Tag vs Custom Tag Cloud