KEF Reference 3 or Raidho X2?

These are very different speakers in terms of power requirements, room requirement, sound profile and soundstage presentation. 

Kef is a classic "cone and dome" speaker.  The image is presented to you as if the performance is in front of you.  Raidho is a ribbon and delivers a more immersive sound.  The sound reflects off the walls to create the soundstage and it feels like it surrounds you.  Neither is good or bad.  Just different. 

The Kef's are a little brighter and require careful toeing.  Tonally, your equipment should work well unless your room is under-damped.  The Raidho's are more natural and less sensitive to what they are matched with.  It will be reasonably natural unless your room is overdamped in which case it will drift dark.

From a power requirement, the Raidho's are easy to drive and work well with tube gear.  In a normal size room, 50-75w is plenty.  Kef's like a bit of power and are a touch more difficult to drive.  I like 175w to drive them.  

For room, the Raidho's NEED 3' behind them from the wall, minimum and 9' of space between them.  If they don't have that, the soundstage will not come together properly.  Proximity to the sidewall is unimportant. Kef's should not be as difficult to place and will be more flexible.  

You will need a subwoofer with the Raidhos.  You may or may not want one with the Kefs as their bass response is much better.

Raidho pricing is a topic of debate and is better left as a conversation between you and your dealer.  

FYI..I am a Raidho dealer.  I am not a Kef dealer.  

Vandantaudio, Thanks so much for the comparison. Please advise if it is common for the seal ribbon tweeter of Raidho to wear out and become sagged. Though the sound is still good, would it get worsened soon. What is the cost of getting a new ribbon? Is it worthwhile to replace it?
Thanks again！

I have not seen an issue with a sagging tweeter.  The first I had ever heard of this was in another thread. 

@verdantaudio I am really impressed by your posts. You really add a lot of value to the conversation here.

The first thing I would ask is whether you intend to purchase either speaker un-auditioned ? Asking others for guidance or opinions is not really the best approach. Unless you have a lot of cash to throw around, I strongly suggest that you make arrangements to audition both speakers. I realize this could be a challenge. Locating a distributor for either of your for mentioned choices can be very difficult. Especially in the case of the Radiho. I think their dealers a few in the US, unless you live out East. In New York, for instance, I'm certain you will find a dealer for both brands.
From that point on, "use your ears". This the only true way you can solve this choice issue. Personally, I don't feel that either one would be on my short list, but that's me !