I'm Level 66:
Gouriki's Meeting Point Hell took 4:36 and gave 10734 pooled experience (SS=32202)
Secluded Forest Hell took 5:44 and gave 14695 pooled experience (SS=44085)
And then I tried the Estate, only had done it the once for the story so I was not as familiar:
Echigo Estate Hard took 7:14 and gave 19545 pooled experience with the daily 30% experience, so it would normally be 13682 pooled experience (SS=41045)
Yesterday I ran Jellyfish Cave Hell for the first time trying to be safe and not die and it took 13:22 and gave 45,319 pooled experience with the daily 30% experience, so it would be 31723 normally (SS=95169). But even if I could do this faster it would still be pretty inefficient just because it is so far from the repair area. I did Hard as well and it was basically the same as Secluded Forest Hell, but still too far away from Partner NPCS. It takes about 2 minutes and 40 seconds to repair and re-enter the dungeon.
Echigo Estate Hell took 17:11 and I got wrecked dying 3 times
It gave 43,182 pooled experience with the daily 30%, so it would normally be 30227 experience (SS=90681) Which was actually worse than Jellyfish Cave Hell for me in the 1 run for both I did. Although I played really bad in the estate I think playing safer just to get the SS like I did in Jellyfish Cave would still be worse than just doing Jellyfish Cave.
But yeah at my level, at least solo like I usually am, Secluded Forest is still the best. Haven't tried Marlin's Den much but I remember it having some pretty annoying enemies as well, and I did run Plover pit yesterday but don't remember how much it gives, but like Jellyfish cave it is far from repairing NPCS :\.