I've tried a bunch of power amps and had different results with all of them.
If you're looking for a "modern" metal type sound, I recommend putting it through the FX return of a high gain amp head or combo, or really anything with big fat power tubes. I've been running my MP1 through a Jet City 333, 100 watts with EL84s and it sounds
huge for those metal chugging riffs. It
does color your sound a bit, which might not be a bad thing for what you're looking for; it's all a matter of preference.
I've also run the same setup through the effects return of my Line 6 Spider Valve 112; it's a tube/digital hybrid Line 6 put out for a few years. The power section is all tube, 2 6L6s, and I quite like the sound of this. For 40 watts of all tube power it gets really loud for such a small combo.
For solid state, I've used a MosValve 1160, which is a bit rare. I'm not sure how the 962s sound, though they're much more common and can be bought for ~$150USD. It had a nice color to it, I found it added a bit of brightness and bite and was decently suited to metal. It really shines on cleans, plus it looks nice in the rack
I've also run a Marshall Valvestate 8004. This is the younger, 40w brother to the 8008 and lacks the controls on the front panel; it's either on or off, so you would need to use the last item in your signal chain to dial in your volume. I believe it has 1 tube in there, but I think it's just for show. I've seen Ola Englund replace the tube in a Valvestate head and get radically different results, so I could be wrong. Otherwise, it's solid state but very very good, especially if you can get the 1U version. There's a linear switch on the back so you can A/B which route you want to go. I've played my setup through the 8004 and through the power section of a JVM410 and liked the 8004 better.
My main power amp now, however, is the B200s. Something about it is just the nicest, cleanest sound, to my ears. I've been using it for my cleans and leads when recording, and when gigging with my casino band it gets the range of tones I'm after. Again, if you want that modern metal sound, you might want to look elsewhere, but do give it a try if you have the opportunity. It has a nifty plug on the back too, just in case you need an extra one.
Those have been my experiences with power amps. I've liked them all in different ways, and I've had a lot of fun comparing and contrasting them; that's half the fun of building your rig! Given your budget, I think you're set to get pretty much anything you want outside of the T100s, which is really rare and apparently weighs a metric ton. I've always been curious about the Engls and Mesas, but can't justify spending $600 for a power amp when I already have a bunch