Hamilton lamps have a reputation for color drift and poor long term performance. I've also worked with lots of people on here who suffered very premature lamp failure.
That said, I've got two halide systems running Hamilton lamps and have not had an issue, but I haven't exactly put a meter on the lights either to see exactly how they are doing.
My new tank I used the XM lamps that Acrylic hates.
I used XM 15Ks. So far, they are pretty good, but again, I haven't actually measured the PAR output myself so perhaps I could be doing better.