@elf4o
Here's the issue with answering your questions. People love to answer questions here on the AH. We do it all the time. But, in response to your inquiry there is no real answer because you have no defined problem or shortcoming with your existing KEFs. How will you know if a new set of speakers is a true upgrade if you don't have a defined problem to overcome? One of the sources of dissatisfaction for people who upgrade is not having a clear sense of what needs improving. Then, when they buy a new set of speakers, they are often disappointed because they aren't "better" than what they have.
Another difficulty with answering your question is that
@TLS Guy is one of the sharpest people you could ever correspond with on the subject of speaker performance. He has said very plainly, your KEFs are better than what you are considering. The real answer appears to be adding a subwoofer to the bottom end. I can't say it more plainly, if
@TLS Guy gives you a direct opinion then you have an excellent answer you aren't likely to exceed.
How to move forward? Set aside some time for a dedicated listening session. Don't rely on what you've already done. Do it new with a purpose. Set aside an hour or so, get your most favorite recordings, and listen to see what it is you don't think the KEFs are giving you. Find a way to describe that. If you like tools, have a computer, and want to get very specific, try REW or other measurement software and measure what you are hearing.. Then come back. Its not uncommon to have to spend a LOT more money on a speaker to get a true upgrade. Buying new speakers is easy. Getting a true upgrade is often expensive and time consuming. Give it a whirl.