Greg - SiteOrigin

A lot of themes ship with Timthumb because it allows their users to start using the theme without rebuilding thumbnails.
Secure Image Resizer offers a far more secure alternative. It allows theme developers to rely on WordPress’ own image resizing functionality using <code>add_image_size</code> and <code>get_the_post_thumbnail</code>.
When get_the_post_thumbnail is called, Secure Image Resizer checks if the requested image size exists. If the image doesn’t exist it dynamically creates the resized version. It works in the background, with no front end functionality.
Theme developers can either bundle this plugin into their themes, or suggest that their users install it.
It also includes 2 functions <code>so_resize_custom</code> and <code>so_resize_custom_html</code> to do dynamic image resizing using Imagick. Great for theme developers.
Please Note: This is an early release of Secure Image Resizer. Please use it, try and break it and report any bugs to me support@siteorigin.com so I can quickly fix them and work towards version 1.0.

Secure Image Resizer

A very simple and secure image resizer. It adds dynamic resizing so you don't need to regenerate thumbnails when you install a new theme.

Bruno Cantuaria

Most users like to upload their fresh shotted pictures to WordPress directly from their digital camera, and what happens? Full disk, reach bandwith limit and slowdown the site with heavy images.
Limit Image Size is a smart plugin wich will limit the megapixel an image can have. When you upload an image, plugin will check if it have more megapixels than you limited, if so, the plugin will automatically resize the image to have that megapixel. This will save space in disk, site’s bandwith and will make your site faster.
Limit Image Size works with 3 methods to resize, not all of them will be enabled on your site but the plugin will choose the best one available for you. The 3 methods are:
<ul>
<li>ImageMagick – The best method with the best performance, but requires that your host have installed the ImageMagick extension on your server.</li>
<li>WebService – This method sends a copy of your image to a webservice which will resize it and sends it back to your site. It’s not the fastest way but is a good one for limited sites.</li>
<li>GD – This method is native to PHP but demands a lot of processing from your server. The plugin will use it only if no other method is available.</li>
</ul>
So, there is no cons to Limit Image Size. Just install it and you will never more need to care about the size of your pictures.

Limit Image Size

Limit Image Size will save space in disk and bandwith resizing large images when you upload them to WordPress.

Secure Image Resizer vs Limit Image Size