Sadhan Pal

Login Login Logo allows you to personalize your WordPress login page by replacing the default WordPress logo with your own custom image. 
With a simple interface and live preview, you can brand the login page to match your website or business identity.
Features: 
* Upload a custom login logo directly from the WordPress media library. 
* Set logo width and height with min/max dimension validation. 
* Preview the logo before saving. 
* Clear/reset the logo with a single click. 
* Lightweight and easy to use.
This plugin is perfect for agencies, freelancers, and site owners who want to add a professional touch to their client or business sites.
<h3>License</h3>
This plugin is open-source and licensed under the GPLv2 or later.

Cute Login Logo – Upload Your Own Custom Logo for Branding in the Login Page

Easily customize your WordPress login page by uploading and displaying your own custom logo with adjustable dimensions and preview.

allilevine

This plugin adds an options page (Settings > Login Screen) that allows you to customize the WordPress Login Screen (wp-login.php). You can:
<ul>
<li>Upload a custom logo (it will be resized to fit if necessary)</li>
<li>Choose a link color</li>
<li>Choose a link rollover color (defaults to a darker shade of the link color)</li>
<li>Choose a button color (defaults to a button version of the link color)</li>
</ul>
The plugin also links the new logo to your site URL.

Simple Login Screen Customizer

Good

Choose a logo and link color for the login screen.  The plugin will do the rest.

Cute Login Logo – Upload Your Own Custom Logo for Branding in the Login Page vs Simple Login Screen Customizer