I'm not sure what exactly you are asking for. Do you mean for the Prompt to return the arbitrary string rather than what it matches in the list?
If so, then MACRO: Spotlight Search Prompt by @DanThomas might be a good choice for you. The default is to return the matched string in the list, or it alternate value, or whatever you want when you add a custom button. I have been using it extensively to do just that.
What I desire is a blank text entry. For my application, I can't be required to choose from a list.
"Prompt with List" is very close in terms of efficiency and functionality, but it tries (requires) to match from a "list" before it will accept an entry.
I need to be able to type anything and the tool accepts it.
Apples and oranges.
Spotlight and LB are for finding/matching lists of something -- not taking a users input and passing it on to other statements in a program/script.
You can reduce Prompt for User Input to one field and one button:
OK, then. I guess LB is the tool to use for this.
AFAIK, can't be done in native KM Actions. Even @DanThomas' Spotlight Search Prompt displays a window with a button.
However, I suppose you could use the KM Custom HTML Prompt action, and write your own web page, but it would be a lot of work.
If it is really that important to you, I guess you could use LB with a custom Action that takes your input and then triggers a KM macro, passing the input as a parameter to the Macro. Then use the %TriggerValue% token to read the parameter.