IF I were to get one, which I have no plans of getting one, I would get a non-WTC/Ironman branded one such as the last one you show here. I don't think it's appropriate, or as meaningful, to get a company's trademark as it is to memorialize your personal accomplishments or experiences.I am not a billboard for a company's product; I am a person much deeper than a company ever can be!
I think it's something to really proud of, but I would never get a tattoo myself. It's really up to you. Plus these ones all look really big, maybe get something smaller if you want one.