IMO, None of them are good for branding. The best one is which has nothing to do with your business. (Example: Apple has nothing to do with computers, Adidas has nothing to do with sports equipments)
It gives you leverage to take business in any direction. For example, if your naming business becomes huge success and you want to start naming more things - like OpenSource Projects or simple apps - the word "Startup" in your name is gonna make you think twice.
I wonder what names you'd give out when you yourself have a bad name, IMO. Any sample names you've created?