I think they're all okay, just the colon seems superfluous. But hey, the symbol seems to have grown on you and you're the creator, so it's fully your call. 
So after some testing the clear winners are:
[~]/>execute
and
[~/]>execute
If I'm understanding correctly the 2nd option should be more accurate. Cos you're taking away the hostname and user for space reasons, but you're working in some unspecified directory below the home directory and then the prompt. Whereas in the first one the / is part of the prompt and doesn't really do anything?
These sadly don't fit on anything smaller than 1.5u but it's workable.
You are definitely getting there... the second one looks good to me [~/]>execute
The ~ character represents the "/home" folder in many many Linux distros, and that is usually the default when you open a command terminal and is where all your personal stuff is stored. As geewiz said, most users customize the prompt in some way so there is no hard and fast rule, so you could use #, $, :, > as the last character before the word in the legend. For instance my prompt is crazy cause I use astronaut. I don't recall ever seeing the '>' char in a prompt but as I said if you think it looks good that matters too.
Here is what a Debian and Ubuntu (super common distro) prompt default looks like these days for instance:
username@debian:~$
with either a blinking _, solid rectangle, or | representing the cursor position. You can include that or not up to your taste.
this format is super common nowadays. If you google terminal prompt you may get inspired as well. As said earlier in the thread lean more towards unix / linux look and keep away from the matrix hacker look. There are plenty of "futuristic matrix vaporwave hacker dude" looking sets as is. Keep up the great work.
