Interesting how heavily everyone's lists are weighted towards the 20th century. Many aeons ago (read: last year), I wrote an exhaustive dissertation (read: superficial 20-page essay) on how the concerto essentially experienced a revival in the 20th century after a comparatively low ebb during the 19th. I think the specific examples of composers I picked as reinventing concerto form to suit their needs were Bartók, Hindemith, Carter and Berio, but there could have been others, those are far from the only 20thc composers for whom concerti (or at least works for solo + ensemble) were relatively central.
(Inasmuch as it makes sense to talk about a "low ebb" during the 19th century. Lots of works for solo instrument + orchestra were composed then as well of course. But most of them jettisoned a lot of the ideas of a "concerto form" and became simply orchestra pieces with a solo obbligato—e.g. Mendelssohn's violin concerto is essentially a symphony with violin, Liszt's piano concertos symphonic poems with piano etc. Only the more "classicizing" composers like Brahms really focused on trying to create a concerto dynamic.)
As I may have mentioned before I don't particularly like the violin (sorry Tobias). That said, another reason for my perception of a "low ebb" is that any top 10 list of violin concerti for me would jump straight from Bach to a few selected 20th century works (Prokofiev 2, Dutilleux, Ligeti, etc) with only the Mendelssohn, the first movement of the Chaikovsky and the adagio and finale of the Brahms (and possibly Bruch 1 and bits of Dvořák—I'm also somewhat intrigued by the Joachim concertos, which I've never heard) standing out in between. I've never been particularly taken with Mozart, Beethoven or Schumann's VCs, Paganini's are charming but a bit too lightweight to sustain my interest for the full half hour or so, most of the others I've heard are pretty forgettable. Some of that could of course be the performances—as with sopranos (sorry Neil), there are very few violinists I can tolerate
In rough order -
Bach - the D minor, reconstructed from the keyboard concerto BWV 1052
Bach - the E major
Bach - the A minor
Prokofiev - the G minor (I prefer it to the D major for some reason, almost no one else seems to)
Bartók - #2
Space reserved for unholy Chaikovsky/Brahms violin concerto hybrid with the first movement of the Chaikovsky and the second and third movements of the Brahms (hey, they're both in D major, roughly similar lengths, it could work!!!)
Stravinsky -
Mendelssohn - the E minor
Ligeti -
Dutilleux -
L'arbre des songesBerio -
Coralehonourable mention: Hindemith, Kammermusik No. 4
There aren't that many violin concerti I feel strongly enough about to
dislike but some of them would include Glazunov, the Szymanowskis, Khachaturian, Shostakovich's C-sharp minor, Maxwell Davies, and Adams. Perhaps I just haven't heard sufficiently convincing performances though.
I don't know about "unsung" ones, but among lesser-known 20th century ones that elicited more than a "meh" I would name William Schuman, Nikolay Roslavets #1, and perhaps Witold Lutosławski's
Chain 2. Also liked Stephen Paulus's once upon a time but haven't listened to it in years.
