I would go for the ISCO II on price/performance, but that does depend on how much your friend is selling it for.
I sold my Prismasonic H1000 lens when I got an ISCO II because the ISCO was sharper (I bought it just to see and was going to sell it on if it wasn't any better). The newer prism based lenses have a corrector lens which helps improve sharpness but the ISCO has an astigmatism adjustment which you can dial in, so I would imagine it would be better (I've not done a direct comparison myself so I'm assuming).
I would think of your choices, the HD6000M would be the best lens but might be quite a bit more expensive than the ISCO II. I was lucky to pick up a used ISCO II from this forum in 2005 for the equivalent of £615 inc delivery, and then got another from the UK forum for a friend for under £500 in 2007. Judging by the prices on ebay, they can be quite a bit more than that now.
Prismasonic used to do a 14 day trial period where you could try the lens and return it if you didn't like it. If you bought a Prismasonic lens and your friend allows you to compare it with his ISCO II, you'll have a good idea how the ISCO compares and buy accordingly.
The only drawback I remember having with the ISCO II was that it magnified the image vertically by around 5%, so when removing it for 16:9 content you had to tweak the zoom a little. Because back then HD was rare and most of my viewing was SD, I just left the lens in place and scaled 16:9 material. I was using less of the pjs resolution for the image, but it was still more than the source res so wasn't a big deal. If most of your watching preference turns out to be 2.35 stuff, and you don't mind losing some res for HD 16:9, you could go that route for simplicity.
You will also find that when comparing lenses using test patterns which tell you quite accurately how each lens performs, you will find the differences are less obvious with video material. So if cost/value is a concern, you might find the ISCO II is the best bang for your buck (depending on price)
I used my ISCO with a 2:1 throw and a pj with a recessed lens, It had some pincushion (as do all lenses to some degree, depending on throw) but I could easily lose that with a little overscan into the screens velvet border. A larger lens may help reduce that a little.
None of the lenses you have in your lest are bad lenses (and the Panamorph does get good reviews) but I personally would go for a cylindrical lens, given the choice. The HD6000F is probably the best of the bunch you mention.