The key here is to sit on these bikes, determine how well it fits your body and posture, and take it for a test-drive.
So generally it's been adviced to try any one of these to start on:
1. Kawasaki Ninja 250/500
2. Suzuki SV650/SV650S
3. Honda VTR 250
4. Suzuki Katana 600
5. Suzuki GS500F
6. Early 90s F2/F3
7. Others...
Number 1 being the safest to learn on, but people have reservations against it. Since it looks it came straight out of the 80s, and it might not be comfortable for people of certain stature.
Number 2 is probably a lot more popular, generally appeals to the wider crowd. Good looks, naked (means if you drop it, you won't have any fairings to replace). And with the given power, it satisfies the rider for quite some time before moving onto inline 4s. Still have to be careful of the low-end power when you roll the throttle. The '03 of this bike is the best bet out of all the bikes listed IMO, since it comes with fuel injection (no carbs cleaning, hehe), and a neat looking digital speedo.
3. This is also a decent bike, after all, it's Honda. But much rarer to find one for sale, most are usually '89 or prior to 90s.
4. It's an inline 4, comfortable ride like a tourer. But a bit on the heavy side.
5. More or less the same as number 1. But people find number 1 bikes a bit more flickable, less heavy, more power, and more popular.
6. This is for all the people who want inline 4 600 power straight out of the box. The earlier 600s don't have nearly as much powers as today's do, but you can still mess up on it faster compared to the ones above. Basically, gently roll the throttle everytime during first several months of learning stage.
7. Is all the rest... '03-04 R6, Gixxer 600, ZX-6R, CBR-6RR, people who are bit impatient and fixated with looks, go straight for the race replicas. Also bigger balls and sometimes less brain matter is required.
The middle-ground between 6 and 7 are bikes such as '03-04 F4i and YZF600R. Power of today's inline 4, but much lenient on the rider in case he/she screws up.
So you have to see what's compatible to your criteria: price, how well the bike suits you, availability depending on your location, condition of the bike, deals you get, etc, etc.
Also if you use the search function and type in "First Bike," it will give tons of related topics.
Rider Safety 101:
http://www.automotiveforums.com/vbul...6&goto=1949346