Guitar Jam Tracks - A Site by Site Comparison

As a lead guitarist, I'm always on the lookout for guitar jam-tracks. However the online sites appear to be a piecemeal collection, ranging from hard-sell sites pushing complete packages on you, decent sites that are swamped in flashing advertising banners to hobby sites set up as blogs with a handful of oddly named tracks
After getting lost and frustrated in the morass, I decided to systematically compare the sites in order to answer a simple question:
Guitar jam tracks - which single site offers the most features?
After poring over Google searches I had come up with the following - alphabetically ordered - 16 sites as potential contenders:
- bluesblast[dot]
- datamusic[dot]org
- easyleadguitar[dot]com
- freejamtracks[dot]com
- guitarbackingtrack[dot]com
- guitarjamtracks[dot]com
- guitarjamtrackshq[dot]com
- guitarlessons[dot]com
- guitarplayback[dot]com
- guitarteacher[dot]com
- guitarvoice[dot]com
- heartwoodguitar[dot]com
- jamcenter[dot]com
- jamtrackcentral[dot]com
- jamtracksforguitar[dot]com
- practicesoloing[dot]com
The above sites were examined for the following features. These features are purely subjective in that they are important to me. Others users might have similar or different criteria. Also, the features are not weighted, meaning they are, to me, all roughly as important as each other:
(1) Users can submit guitar jam-tracks
(2) The tracks are ordered by key
(3) The tracks are ordered by date
(4) The tracks are ordered by genre
(5) There are tracks for every single key
(6) There is a mailing list
(7) Users can post comments in a discussion area
(8) There are scale charts available for each key
(9) There is a video instruction area
(10) The tracks can be previewed
(11) The tracks can be streamed
(12) The tracks are downloadable
(13) The tracks are accurately and precisely named
(14) The tracks are studio production quality
(15) The track names contain the chord progression information