ok, first off a monster is not a sports bike, it's actually a standard style bike made by a big sportsbike manufacturer.
In summary I don't like either of your choices, with the monster you get some good performance (not nearly that of a real sportbike) but your paying an extra few thousand dollars just for the name ducati on the side. Maintenance will be through the roof and it's kind of nice for a starter bike.
on the other hand you have a HD sporster, I hate HD and everything it stands for, but even if I didn't this is a bottom of the line model, and again your paying extra for a sticker on the tank. Maintenance will be even more expensive than the ducati, and it has performance like a mini van.
I like the blacked out cruiser look too, the way I see it there'll be plenty of time to ride a cruiser when I'm too old to twist my body onto a sportbike.
your nineteen, live it up, look for a 00'-02' CBR 600RR
and just btw, I wouldn't recommend that you spend more than $3000 on your first bike, it's gonna get banged up and probably wrecked anyhow!