Depending on whether you are looking for management reports or servers ease at order entry will determine your end product. I think Squirrel is great for reports and the ability to edit the information for order entry, menu modifiers and menu changes. The downside is the use of a card for the servers. The cards get lost and they are costly. I am not sure if there have been changes to their card system lately.
Touchscreens are the easiest for servers to work on in a fast paced environment.
Aloha is a low cost touchsceen that many servers have enjoyed working with, however, I have not personally worked with the system itself. Decide what your end information is and what reports are most important to you. From that information you can find out what systems are set in stone and which systems are able to conform to your needs. As with any computer system, it is important to set it up correctly in the beginning, to avoid the pitfalls during daily operations. With any menu change, the computer needs to be updated and maintained on a daily basis.