I also started out with a CBR 250. Specifically it was a 1992 CBR250, absolutely loved it!
Have you seen the new 2012/2013 CBR 250's? If i wasn't in the market for a higher-performing motorcycle, I would be looking at a 250 right now.
The first bike I rode was a 1960 ish Honda C100 (50cc Stepthrough) when I was about 8, first bike I owned was a Yamaha TY175 trials bike when about 12 and the first bike I used on the road was a Honda TL125.
Stopped riding when I was about 22 and got back into it 4 years ago when I saw a cheap CBR600F for sale one nice, sunny day!
HD Sportster 1200. Was alright, but after 4 yrs of riding it I concluded (2yrs prior) that cruisers are not for me. The suspension blew and the vibration between 80 and 120 kph was redonkulous. Was like riding with a 2x4 up the keester. Wld never reccommend a Sportster to anyone, especially for a first bike.
My first road bike was a 1974 Kawasaki S3 400 two stroke triple. I bought it in 1980 when I was 16 and had a blast. It would lay down a smoke trail to make 007 proud, vibrated like crazy and got terrible mileage. The fun part was it would almost pull your hands out of the sockets when you took off. I trust this new Honda 500 will be a bit more refined and cleaner.
I started on a "generic" 50cc scooter made in the back alley in some third world country i'm sure, but after about 3 months of constant near misses from car / truck drivers overtaking i thought it better to take my test and get a proper bike. I would recommend that no one ever start on a 50cc they are just plain dangerous on the road because they are just too slow.
So my real first motorbike and current one is a CBR250RA 2011 model