Well, seeing how you won't be able to get your hands on the 5th gen iPod Touch for a few weeks, and the looming rumors of iPad Mini. I would say wait it out until the iPod is out. Then go play with the thing. iPhone, well you will need to pay for service so that might not be a fantastic option unless that is what you were going to do any way.
I have an iPhone 4s and it does it job. I also have an iPad two so best of both worlds. For someone with none of these, I would say that it really depends on overall needs. If you need a portable device that keeps you in contact pretty much everywhere, then the iPhone is the way to go. IF you need the same and don't mind a larger device, then the iPad will do just about everything the iPhone will do minus a small package.
Its your call, you know how and what you will use and what best suits your needs. I would still say wait till mid October to see if the iPad mini is unveiled. If you are in no immediate rush, its your best bet to have everything to choose from.