I didn't know you were a Hendrix fan, Mick.
Anyway, I feel Band of Gypsys is his strongest... I mean, the band is just very interesting, the way they go about a live performance. The way they experiment with the music cutting in and out, constantly withering down to a nearly inaudible level, is very original for the time the album was released, not to mention they do it all live, which sort of creates a very atmospheric environment. The first two tracks are amazing, as are the rest. And, personally, I think it's just a downright sexy album, if that makes sense. I don't know, I just think it has sort of a sexual energy to it which isn't present, or at least as heavily present, on anything The Experience ever did.
If I were to clump both of his bands together to simply rank Hendrix's core releases, I think it'd look like this at the moment:
1.) Band of Gypsys (1970)
2.) Axis: Bold as Love (1967)
3.) Electric Ladyland (1968)
4.) Are You Experienced? (1967)
I don't know, maybe swap the last two, depending what sort of mood I'm in... If I want some really heavy psychedelic-rock, I go for Are You Experienced?