Tone King Royalist MKII Tri-Tube Preamp

It's a Tone King product, so it's obviously very high quality, carefully crafted, you can feel it with every touch.
It does almost exactly the same thing as the Imperial Preamp, only modelling different amps, and with some new switches, you have more options to shape the tone. It lacks tremolo, though the music you want to play with this probably doesn't require it anyway. It's versatile, the channels are different enough that if you combine with the voicing options + built-in IRs, you can really squeeze a lot of tone out of it.
My only real criticism is that it sounds too bright, sometimes even harsh. Even if you set the maximum high-cut from the software, it can still result in ear fatigue after relatively short playing.
It sounds very harsh through Adam Audio A7V speakers, but it's much better through my Laney LFR-212 cab with the right IR.
My favourite, the Imperial Preamp (I own both the combo amp and the preamp), sounds so insanely good right out of the box that I didn't even look at the software options for months after I got it. With this one, the first thing to do was to open the TK Editor to see what I can do about the hashness.
It's a great preamp that sounds better than any modeller and can make great tones, but I HIGHLY recommend an EQ pedal (my favourite is the Empress ParaEq MKII Deluxe) and some tinkering with the software.
However, the Imperial Preamp remains the king.