Yourmusic Productions' opinion of various edos
(Shamelessly stolen from CritDeathX's page of the same topic.)
1-4EDO: Contained within 12 and so not worth talking about.
5EDO: The emancipation from harmony. Nothing clashes with anything else, so you're free to play any combination of notes and concentrate on rhythm, arrangement and instrumentation instead. (and you really need to push those other areas to keep it from getting boring.)
6EDO: A universe in monochrome. You can make things out, but so much is missing.
7EDO: The emancipation from harmony, but now with recognisable, if bland diatonic melodies.
8EDO: Any combination of more than 2 notes sounds bad, and most 2 note combinations sound bad too. Just vile.
9EDO: Marvellously elegant little system. More than enough room for complex melodies and fortifying them with double-stopped 3rds and 6ths sounds awesome.
10EDO: A universe that's recognisable, but everything is distorted and the people have no faces. The merging of 3rds and 6ths removes one of the primary forms of textural expressiveness in 12, leaving it disconcertingly emotionally flat.
11EDO: It can almost pass for 12 as long as you only play one note at at time, but more than that and it's limitations become painfully clear.
12EDO: The more I study it, the more it's flaws and limitations irritate me.
13EDO: All the various kinds of 9thno5 chords work, and have interesting new flavours compared to their 12edo equivalents. Well worth getting to grips with the cluster based harmony needed to make it sound nice.
14EDO: The opposite of 10 - recognisable, but distorted so there's three types of 3rd and 6th with exaggerated expressive qualities. Even though it's best intervals aren't as in tune as 12, it sounds much less dissonant when playing all the notes at once, so it seems a natural home for Schoenberg influenced serialism and extended chords.
15EDO: Like 14, not as good at simple harmonies as 12, but some glorious extended blackwood chords that combine more notes than you can in 12 and still sound good. Porcupine looks simpler, but I actually find it more of a struggle than blackwood to use.
16EDO: 12's evil twin. Scales are recognisable but inverted and everything but the mellowest of timbres or simplest of harmonies sounds horrible once you start combining notes.
17EDO: Interestingly alien, but with good 2nd's, 4ths & 5ths to retreat too when you're not sure what to do next.
18EDO: A universe in monochrome, but with extended dynamic range. There's enough complexity in other areas to keep it interesting, but I'm still aware in the back of my mind that something's missing.
19EDO: The more I study it, the more I love how elegantly everything fits together, how you can use standard notation, but things that are equivalent in 12 actually have proper meaning here, how familiar tunes are transferable and recognisable but the emphasis on intervals is subtly shifted to making minor chords and melodies sound more stable and consonant than major ones. It still has it's limitations, power chord based heavy rock in particular suffers from the weaker 5ths, but just works so much better than 12 in general.
20EDO: Looking at the math on paper, it should be possible to create pleasant music in this one, but nothing I've heard has actually managed it yet.
21EDO: Like 14 but moreso. Dramatically exaggerated harmonic expressiveness, shares the relatively nice major 3rd with 12 rather than the horrible tritone, and the highest edo that works with standard notation without having to add more letters or learn new kinds of accidental. Not as good as 19 for familiar sounding intervals, but still really rather nice.
22EDO: Like 24, only the new harmonic options are actually more in tune than the familiar ones rather than less. Better than 12 but still not quite as good as 19 overall.
23EDO: Not enough songs using this to get a proper opinion. Definitely one of the tougher ones to get to grips with.
24EDO: Double the complexity, but considerably less than double the number of good-sounding combinations. A lot of extra work for little extra return.
25EDO: The whole-tone version of 50EDO's golden meantone. Lots and lots of bad options but like 6 vs 12, missing most of the good combinations.
26EDO: Definitely deserves more attention than it's got so far.
27EDO: Like all pure powers of 3, unusually good for it's size. All the melodic coolness of 9 plus decent minor and neutral intervals and an acceptable 5th. Definitely my favourite superpyth system of manageable size.
28EDO: 14, only with a really in tune major 3rd and lots of other really interesting extra intervals. Really want an instrument that can do this one justice, probably an 8-string guitar tuned in it's slightly stretched 5ths so the top string is 3 octaves up from the bottom, and a 28-30" fanned fret multiscale fretboard that makes all the chords isomorphic.
29EDO: 12's evil twin, but in an awesome way. About the same amount of error but in opposite directions means similar kinds of psychoacoustic beating, majors and minors are still clearly recognisable, and everything sounds deceptively familiar right up until it does something awesome that 12 can't. When you do focus on xen intervals and chords, it still sounds much better than 24. Another definite favourite.
30EDO: Whole tone + Blackwood. Like 24, mainly just adds more ways to sound bad compared to 15 and not worth the hassle.
31EDO: It definitely sounds nice, but I don't hear much actual songwriting going on in it, just people building enormous washes of harmony and luxuriating in them. Maybe it has too LITTLE tension in it, or maybe it's just past the point of complexity that the human mind can fully comprehend. In any case, it definitely hasn't been used to it's full potential yet.
32EDO: Like all pure powers of 2, unusually bad for it's size.
33EDO: Interesting, but another one that's too big to explore properly without better equipment, and nothing I've heard yet has really managed to do it justice.
34EDO: Even better for 5-limit music than 31, with it's gorgeous thirds, actually defined different sizes of whole tone and still sour harmonic 7, yet even more underused. Definitely deserves more attention. Maybe a half-kite guitar, with full frets up to the perfect 4th or 5th, then 17edo above that point, with adjacent strings tuned so the full range of higher notes can still be played would make it feasible.
35EDO: The highest EDO that absolutely refuses to fit into a diatonic framework and forces you to work with it on it's own terms. If you do, it's ability to combine whitewood and blackwood make it incredibly flexible, with very interesting extended harmonies. Something like a 14 string chapman stick with one side tuned in 3 octaves of stretched 4ths and the other in 2 octaves of compressed ones would properly highlight and take advantage of it's unique strengths.
36EDO: 12, only with lots of extra harmonic options that actually sound good and are much easier to slip into an otherwise normal track than 24's.
84EDO: 12, only each note is split into a full rainbow, which makes for awesome looking yet still easily comprehensible notation. The best multiple of 12 for 5 limit music and my personal holy grail of edos to find a way to make playable.