Are you looking to get your first bike new or used? If you’re planning to go with a used bike there is probably more availability with the Ninja 500 or take a look at Suzuki’s GS500F (which is what I have). Going with a used bike for your first one eliminates a lot of the frustrations when you drop the bike to the pavement. We’ve all done it a time or two, it DOES happen with the first one.
However, if you’re into getting something new, the Ninja 250 or 500, or GS500F are all good choices, if you feel comfortable on them. I was glad I picked the 500 and not the 250 to start on myself, but I live out in the country where most of my driving is 55 mph or higher.
Yes, the Blast has the negative point mentioned above, but it also has a belt instead of a chain, I think, which would reduce your maintenance. One other bike to consider… the new Honda CBR250R. Wow! If it had been around when I bought my first bike, maybe I would have gone with a 250.
Very wise choice to take the class before you make a purchase! Good luck with whatever you choose.