Paradigm 3f, KEF reference 3, Monitor Audio PL300II

I've been auditioning speakers in the $15,000 range and am almost ready to decide.  My short list right now is the KEF Reference 3 and the Monitor Audio PL300II.  I'm planning to hear the Paradigm Persona 3f this weekend.  I've also heard speakers from B and W, Wilson, Wilson Benesch and Proac but none made the final cut.  I really expected to be blown away by the Proacs and, while they were very good, I prefer the KEF and Monitor Audio. Unless the Paradigm is even better, it will be a tough call. They both seem to have great imaging and soundstage, reasonable bass and pretty life like presentations.  We all know how hard it is to compare and contrast speakers, especially when there's a large time gap between listening sessions. The Monitor Audio dealer has offered to bring them to my house, set them up and let me live with them for a week at no cost. Sounds like a great offer but I don't want to accept if I'm leaning more towards the KEFs.  Any helpful advice would be appreciated.  
For that price, if you go with KEF, I'd go for a set of used Blades over the Ref 3.
The PL300 II’s are a very well rounded speaker that is great for long listening sessions. I’m very impressed with all of the Platinum II series for the price. For 15k you could get some amazing used speakers. There is really no need to limit yourself to such cookie cutter products.
I have been trying to talk myself OUT of getting a KEF Reference 3 for the office because I definitely will be getting a Blade 2 for my family room. I was thinking it maybe too much of a good thing to have 2 similar types of speakers.

I have looked at exactly the 3 speakers you have listed. I have not heard the Monitor Audio but have read reviews, mostly good. However, the footprint of the Monitor Audio speaker is a little large for my office.I heard the bigger Persona 5F in a terrible room but I liked the speaker because it disappears well. So far I have not been able to convince myself to deviate from the KEF 3 for the office. I love the sound of the new KEF speakers. 

However, recently the light bulb in the brain has made me consider shifting gears for the office and try something out of left field such as a German Physiks Unlimited speaker or some brand using different tech than a dynamic speaker. 

Not sure my ramble here helps you but you will have a good speaker whatever you choose from your list.

I wouldn’t pay $15,000 for any of those without at least auditioning Legacy Audio Focus SE at around $10,000. Focus SE is a more full range speaker than any of those, rated down to 18Hz bass extension, and you get the AMT ribbon tweeter/mid driver. For me, the problem with the Paradigm Persona 3F is that it is a pretty small and bass limited speaker to be paying that much for. It is only rated down to 48Hz. You have to go up to the Persona 7F to get a speaker of the scale of the Focus SE.  Heck, you could get a set of Legacy Aeris for just a bit more than your $15K price. The Monitor Audio Platinum II line has been getting rave reviews, and you can’t beat being able to audition speakers in you own home before buying.
When considering speakers, or anything desired or needed, one just about has to look at what is there in pre – owned. For the same money.

Its nearly well, at least myopic not to do so.

We’re all facing this question from time to time. If possible, take a little road trip and get at least some inkling of the other missing link. Spending this amount just about dictates it. Again, if possible.

IMHO the single issue of contention is warranty, if all else is on a level playing field with what ever seller.

Therefore the question becomes, is my $$$$$ better spent on higher performance or a particular esthetic and assurances, which BTW may well end up forcing me to ship the new speaker off if needs be, just as it could ocurr with the used one?

I’ll say this and close. I’ve had speakers that ranged from 25 yaers old. 30 years old. Several new ones. And some from 2 to 5 years of age. The most ancient of them did eventually require me to get them refurbished and luckly two sets of them could be done by the orig maker. I still have them. The newer ones are all gone. I don’t miss but one pr of the dozen or more I’ve owned. Only the refurbished ones remain along with a couple sets of monitors and all sound just great. Only one pr were of ‘flagship’ quality.

Higher priced speakers usually include more robust builds, especially those one can capture for near double the investment of say $10K to $15K, or $25 – 30K.

It adds to the conundrum, but it’s a nice mystery.

Good luck.