Help needed for upgrading...

I would like to upgrade from Quad 21L2...looking for a similar type speaker in terms of bass extension and punch, and neutrality. Just want a lot more detail and transparency. And want something dynamic but not bright. I have a Simaudio I3 amp, which is considered neutral solid state.

Room is about 18x18.

In my area, I can only purchase the following:
(1) Dynaudio - 220 may have too much bass for me
(2) Spendor - perhaps S6e or S8e
(3) PMC - perhaps GB1i or FB1i
(4) Harbeth SHL5, but I cannot audition these
(5) Dali Mentor 6, although these could be bright with my amp

Does anyone have any experience with one or more of these speakers...
I owned the Spendor S8e for a couple of years in a 17 x 17 x 12 room. Really wonderful sound to me. High passing it when I added a subwoofer made an obvious increase in clarity and detail. I would choose the S8e over the S6e unless cost is the deciding factor.
I have read that Spendor is a "relaxing" sound - would you say it is "realisitic"....

Does the S8e have better midrange and high frequencies than the S6e?
Yes, Spendor's have an enjoyable sound. You can listen for hours with no hint of fatigue. Relative to other speakers I've owned (studio monitors) I would say the treble of the S8e is smoother with less bite (so maybe less realistic). My issue with the S6e is its cost for having a limited bass range. A couple of comments in Stereophile have suggested (and I agree) that the S8e is the best speaker in the "S" line. The 8" woofer/mid is a special driver. You can get away without a sub with the S8e (and maybe the S5e), but not the S6e. So why spend the money on the box. Buy the S3e and a good sub. As I've said, even the S8e shines much better with a sub.
Before you toss the speakers look at your cables and interconnects. I highly recommend Clear Day Solid Core Speaker Cables. You will want these anyway so why not try them with what you own?
If you can, try a pair of Dynaudio Contour 1.8MKII.
They have better and controled bass than the 220 and they are more refined, and also match well with your Moon ss amplifier.
It is difficult to find a used pair but because the age, they are very affordable.
They are not for biwire and work perfect with the cheap Ocos speaker cable.
Good luck
With regard to Dynaudio, I can only get the Contour 1.4 (bookshelf) or 3.4 where I live. Countour 3.4 is out of my price range, and not sure how a 1.4 would compare to a 220? I don't have a sub and I do enjoy low frequency sounds from certain instruments. My current speakers hit -6db at 35hz so they say....The 1.4's are the same price as the 220.

The other options I have heard are Leema Xone, Audiovector's new S3 series (replaces Mi3), or the bigger Ushers...

Anyone have experience with these?