Between KEF LS50 and Harbeth P3esr, it will come down to your preferences in music, as well as what you prioritize in terms of sound signature. KEF is an imaging champion, so if that's what you want in your music, I'd go for the LS50. I owned the LS50 wireless version and really liked them. Crystal clear highs, excellent imaging, the music will come to you as if you're sitting in the first row. However, I found it to be a bit lean sounding, especially in the mid bass region. Also, it can sometimes sound bright depending on the recording.
Harbeth P3esrs (which are a mainstay in my home office system) are the ones that I didn't like much when I first bought them. But, man, do they grow on you once your ears adjust to their sound signature. Very balanced top to bottom, with a midrange to die for. The vocals are about as good as you're going to get in a speaker of this size. I don't know how Harbeth does it, but the way they present vocals has something so natural and satisfying about it, as if the singer is present in your room. They are a sealed design, so placement will be easier compared to the KEFs. Now on the down side, the P3esr's start to fall apart if you dare to go above moderate listening levels. All the magic that makes them so good seems to evaporate. They're also not the most dynamic speaker out there. So if this is something you care about, I would look at the LS50s. And lastly, I felt that the LS50s were more of an all rounder when it comes to casting a wider net for multiple music genres. The Harbeths will do exceedingly well on jazz, vocals, acoustics, classic rock, etc. But yeah, they'll fall apart if you lean towards EDM or heavy metal. You are going to need a small, musical sub (e.g. REL T/Zero or T-5i) to augment the bottom end on either one though.
Hope this helps.
Harbeth P3esrs (which are a mainstay in my home office system) are the ones that I didn't like much when I first bought them. But, man, do they grow on you once your ears adjust to their sound signature. Very balanced top to bottom, with a midrange to die for. The vocals are about as good as you're going to get in a speaker of this size. I don't know how Harbeth does it, but the way they present vocals has something so natural and satisfying about it, as if the singer is present in your room. They are a sealed design, so placement will be easier compared to the KEFs. Now on the down side, the P3esr's start to fall apart if you dare to go above moderate listening levels. All the magic that makes them so good seems to evaporate. They're also not the most dynamic speaker out there. So if this is something you care about, I would look at the LS50s. And lastly, I felt that the LS50s were more of an all rounder when it comes to casting a wider net for multiple music genres. The Harbeths will do exceedingly well on jazz, vocals, acoustics, classic rock, etc. But yeah, they'll fall apart if you lean towards EDM or heavy metal. You are going to need a small, musical sub (e.g. REL T/Zero or T-5i) to augment the bottom end on either one though.
Hope this helps.