After Blackgates... which caps are best for Audio?

Michael Percy...
http://percyaudio.com/
...sells Nichicons including audio-specific types. I installed the KG Super Throughs in my McCormack DNA-750 powersupplies.
http://i89.photobucket.com/albums/k220/jeffreybehr/McCormack/09May2012_newPScaps1_1000w.jpg

I've not tried the ES series for coupling or PS apps in electronics.
.

I have heard good things about Dueland stuff...very good. Gryphon, Tidal Audio both use them in their equipment i have read.

what about about mundorf gold foil oil caps ?

are there any paper oil filled caps of note ?

For electrolytics Elna Silmic II are often mentioned to be the best in production. For film it is probably V-Cap CuTF or Duelund VSF, both extremely pricey, but as always it depends on what kind of sound you are seeking. I have not tried Duelund but CuTF have provided profound improvements for me as coupling caps and with that consideration proven to be a bargain.

... what about about mundorf gold foil oil caps

I use those (Mundorf Silver in Oil, Gold/Silver in Oil) in my Lamm Phono and in
the X-over from my Speakers. They have a very detailed high frequency area
combined with a noticeable transparency in the depth of Soundstage.
I also use V-caps, great, really, but some Datas are really very expensive and for
those I have the Mundorf. Both brands are very good quality, you can't go wrong
with them. Would buy them again.