As an instructor, I take any recommendations I make on the internet a little more seriously than many who just want to justify and defend their latest gun purchase.
The OP had $450 to spend. Why not help him get the MOST for his money?
I have a few friends that own the Hi-Point, and they like them. Don't care for the thin sheet metal single-stack mags, and the overall cheap quality. If you don't care about quality, and are willing to trust your life to a $100 rifle with a handful of rounds in a flimsy magazine...go for it.
Keltecs? Well, I would rather have one than any Hi-Point. But, I could never get a good cheek weld and still align the sights without laying my head to side in a very awkward position.
The PC9 and PC40 were designed for LE duty use. Can't say that about either of the others. My Ruger happens to have a very good trigger, with a crisp letoff. Not heavy at all. It is a little different than other carbines I own. So what. Learn to use it well.
The carbine is accurate, reliable, good sights, points well, uses quality, steel, high-capacity mags (Mecgar), and easily mounts an optic with Ruger's excellent proprietary ring system. My PC9/4x scope will put 5 rounds into 1" at 50 yards, minute-of-eyeball, with Winchester 147 HPs.
BTW, I have owned the Cobray M11/9s before and cannot recommend them either. The "c"-clips that hold the trigger crosspins have a bad habit of popping off and causing malfunctions under any kind of heavy use.
Good Luck.