I use Reflo Powerline, it is thinner for its BS than the others mentioned, this means I can use a heavier BS for the same diameter of line, for a modern low dia line it is quite durable and when treated with line grease floats quite well, conversely when rubbed down with a fullers earth and soap mixture it sinks well enough too.
As has been mentioned, I also only use 50yds at a time (I certainly cannot see a fine float tip 40 yards away) therefore you get two fills for the price of one, most importantly when used with a through action rod it withstands shock well, it also tends to break at a higher strain than that which is stated on the box.
For years I stuck with Bayer Perlon and while Drennan Float Fish is similar it is not as good,
I am told Float fish is from Bayer and that may be so, but it is defiantly not the same as Perlon, which I cannot find anywhere for love or money.