Are Quicksilver power tube amps in the same league as VAC, VTL, BAT, ARC, ...?

Yes they are great. I have three sets of QS amps: Silver 60 (which Mike thinks are one of his best), mono 60, and mini. I use the minis 90% of the time, they are amazing. I also own 2 QsS preamps, the remote and not remote. I have the last version of the non remote, it is outstanding for the money. The remote is 95% as good, and is the one I am using now for the convenience of the remote. I also  have a Parasound JC2 (great preamp), but I like the QS preamps better. I think the QS Mini's have been the best value in audio, unfortunately discontinued now. 

Great question by the OP. We all want our hard earned $ going towards quality. Most of us can't afford to play the high end merry-go-round.

In the past 30 years, I have owned VAC, Conrad Johnson, and Decware amps. I've listened extensively to ARC, BAT (sounds like solid state), Quicksilver, Lamm, Cary,  and VTL. They're all excellent, depending on what sounds you're hearing for. Some of the others spend more on aesthetics, Lamm & BAT for sure. As for better parts, I can say very confidently that VAC, CJ, BAT, and VTL use pedestrian parts. Those companies make extensive use of circuit boards as well. That doesn't make them bad, just an observation. VAC believes in maximizing the most out of the tubes. VAC is also the least friendly to using alternative tubes...kt88s almost exclusively. Not a bad thing, but also limited.
Each of these companies aim for a particular sound. Like others here have said, find what sound you like and get the best gear you can afford. If you like the QS sound, then you can spend more money on the preamp of your preference, or a phono stage, cartridge, etc.
Finally, of all the companies you've listed, I would stay away from BAT as their company infrastructure is now questionable. That means their support may not be there when you need it...and you will need it, we all need it regardless of company or amp. I'm not sure MusicDiirect is the most qualified distributor to help. They are also the least tube like amps I've ever heard.
VAC, QS, ARC, and VTL are known for their quality and service. All but QS, are also known to be very expensive. I'm not sure why given the aforementioned parts quality. On that subject, don't get me wrong, even pedestrian parts are good quality. Basically we're paying for design, marketing, and reputation.

My 2¢.
Great question and the audience you attracted have offered good advice.

@donvito The HD220 is entirely fixable. It’s loosely based on On Semi’s reference design for thermaltrak devices.
The old production non DG designated output devices are End of Lifed but new ones are available on Mouser or Digikey.
Unless your friends tech was the one who replaced the bridge while the output stage clearly had a thermal runaway and fried the whole board, an HD220 amp that pulls standby after warm up is absolutely fixable. It’s just a bit of work and Audio research just doesn’t want to go through the trouble.

@donvito
If ARC boat anchor gathering dust is being given away except for shipping, I would be interested. Feel free to contact me on Decware. I am safebelayer there as well. Or leave me a note on how to get ahold of you or your friend.

I guess they just discontinued the V4 Monos....   im sure something awesome is in the works....