That's a hard question to answer. It's like asking, "What would be a better-paying career - banker, salesman, or actor?" Well, actors can make millions of dollars, but only if they become successful, and most don't.
So, the one that has the most potential to be successful would probably be the bar, but depending on where you live it might be very difficult. What reason would people have to go to your bar instead of others? Do you have a theme planned? Specials? Would it outdo other bars in that area?
Laundromats require a LOT of money to keep running. Our water bill goes up if we use the washing machine a few extra times in a month. Imagine if we were washing nonstop, on thirty machines. But, if you have the money for it and there aren't a ton of other laundromats and there's a need for them, maybe if you keep one open 24 hours, or at least later than other laundromats in the area, and perhaps offer free wifi, you could build a business there. I doubt it would make you wealthy though.
A hair supply store is very specific. Perhaps a hair and beauty store? Think Sally's (http://www.sallybeauty.com). If you have good products and good prices, sure, people will buy from you. Again, I doubt it will make you wealthy, but you'd probably make a living.
So in the end it really depends on your resources, your ideas, and what's available and what's needed in your area.
Keep in mind start-up costs a LOT. You won't get your supplies at the same cost as other, bigger companies because you won't be buying in such large quantities. While you might be able to buy a week's worth of supplies, other companies are buying several months' worth at a time, and the more you buy, the less it costs. There's also matters of insurance, taxes, employees, keeping the books (accounting) etc.
If you've never run any kind of business before I strongly recommend starting a small home business first - maybe making bracelets or something - to see how it feels running it, and get an idea of how to please customers and keep inventory and keep your books.
Good luck, whatever you choose!