MSB is one of the truly elite DAC makers in the world. Given the higher price point fewer people have a chance to hear and interact with them compared to more mainstream brands.
I have heard the Discrete and the Reference. I have not heard the Premier. I have a good friend who is borderline obsessed with his Discrete and is bringing in a Premier for a demo to decide if he wants a DAC upgrade vs. Speaker upgrade.
In this range, it is very debatable what the best option is and a secondary consideration is how you are going to feed information to the DAC. MSB is appealing since it give you the option of an internal renderer or a myriad of first rate inputs giving you lots of choice. It is also neutral to a hair warm of neutral and will show up in any system that way. It will pair well with Antipodes, Pink Faun or Taiko servers.
From a competitive perspective, dCS is obvious but has a much brighter sound signature and often are best with their own internal streamers. This is an FPGA design and delivers elite performance. The Bartok and Rossini are worth looking at if you need some top-end energy.
Rockna is similar to MSB in that it is an R2R. They used to even use MSB ladders in their older models. Nicolae is an absolute genius in terms of design. The Wavedream Edition is in-line with the Discrete in terms of sound quality and the Signature competes with the Premier. You get a bit of a discount because it is made in Romania vs. US or UK. It is also best with it's own server as there is a dedicated connection between the clock in the Wavedream NET and DAC via I2S connection. These are dead neutral and you will see in reviews, description of the sound profile is difficult because nothing really stands out. The biggest critique is they can be a bit boring because they are so neutral.
Playback Design is about to release the Edelweiss which is going to be $15K retail FPGA DAC. Playback's sound signature is very natural and analog sounding which is achieved via crazy internal upscaling. I am super amped up about this one and have it on preorder with an internal player. The Dream DAC at $24K is an absurdly good DAC and they have a fully integrated player at about $30K which is an interesting unit. Despite relatively modest pricing, their is a segment of the audiophile community that believes Playback is the best of them all.
Ares Cerat makes incredible units. The wait time on these can be a bit long as global demand is crazy. They are one of the most attractive units I have ever seen but you may need reinforcement for your rack as they are insanely heavy.
Jadis, Total DAC, Brinkman, EMM and a variety of others also make incredible DACs in this price range. There is far more choice that you would think.