There are alot of great bikes out there. First you have to consider what kind of riding the bike will be used for, then the price you want to pay. If you are looking for a starter street bike I think the Kawasaki EX500 is a good choice, plus there are alot of used ones out there. The Suzuki GS500 and SV650 are also pretty good choices.
If you are really new to riding I would start with a dual sport bike, like a Honda XR250L, a Suzuki DR350s, DRZ400, Kawasaki KLX250, etc. The new Yamaha 250 dualsport bike would be really nice too but it'll cost you some pennies.
Dual sport bikes are great to learn on because they perform fairly well offroad. It is much better to learn to ride in a field as opposed to the street for a number of reasons, but mainly because when you start learning to ride you ARE going to fall. Remember the addage: it's not a question of whether or not you will fall, it's WHEN you are going to fall.
Hope this information was somewhat helpful. Remember, keep the rubber side down.
Just one more thing, alot of people will tell you can start riding on the street and they are right to an extent. The one problem I have with that thinking is that in a crisis situation on the road you have to instictively know the limits of the machine and your abilities. You can't learn those limits unless you are pushing them. This means dumping the bike over, brake-sliding, power-slides, etc. That's why I think people should learn off road.
If you look at all the best roadracers, they all road dirtbikes as kids.