I’m an Audio Research fan and that new I/50 integrated has caught my eye. Hard to go wrong with ARC unless just not tubey sounding enough for some.
Conrad Johnson has been around a long time also always impresses when I hear.
i have not heard the others but they all of course have their fans. I heard some Raven amp once at a show and it was perfectly fine but did not strike me in particular either way. Not as much of a fan from what I read though as some. Not as extensive a track record as ARC CJ or even Luxman but the owners seem to love Raven. Each have their own aesthetic that should also be a factor in deciding.