Applescript get list of running apps?

You can try this

tell application "System Events"
        set AppName to name of every process whose background only is false
        choose from list AppName OK button name "Ok" cancel button name "Cancel"
    end

Try this:

tell application "System Events"
    set listOfProcesses to (name of every process where background only is false)
    tell me to set selectedProcesses to choose from list listOfProcesses with multiple selections allowed
end tell
--The variable `selectedProcesses` will contain the list of selected items.
repeat with processName in selectedProcesses
    do shell script "Killall " & quoted form of processName
end repeat

tell application "System Events"
    set processList to get the name of every process whose background only is false
    set processNameList to choose from list processList with prompt "Select process to quit" with multiple selections allowed
    if the result is not false then
        repeat with processName in processNameList
            do shell script "Killall " & quoted form of processName
        end repeat
    end if
end tell

you can use this script which is much simpler

tell application "Finder"
    get the name of every process whose visible is true
end tell