I've been a fan of the Aircel Supreme for about twenty years, and I've not found a reason to change. I also have a standard green Aircel and an Ultra 3, both of which are excellent. However, for delicate presentation I've found the Hardy Perfection to have a better taper. It won't cast well into a wind though.
I have used a few other makes in the past. I had a Shakespeare Worcestershire floater which was truly awful; in fact the only line I've ever found that was worse was, suprise suprise, a Shakespeare Glider. I still have a Galion floater that I bought over twenty years ago, which is as supple as any line I've seen - and it still floats. I did hear that these were made by Scientific Anglers, which wouldn't surprise me at all. I've not tried a Cortland, though the 444 has an impressive record.
The thing that I find most irritating about floating lines is the colour. If I'm fishing a deep nymph I sometimes use a white line (Aircel Supreme) because, naturally enough, I find it easier to spot on the water. But for dry fly or just sub-surface nymphing (where I don't need to watch the line for takes) I change over to a brown or green line.
I don't merely believe the colour makes any difference, I know it does. 100% unshakeable certainty, through observation and experience*. Yet the vast majority of anglers seem perfectly happy to use fluorescent yellow and orange lines. Not only do they scare far more fish than they catch, just half a dozen of them fishing a small lake for an hour will kill all sport stone dead for the rest of the day. I know there are plenty of people ready to point out that anglers using brightly coloured lines still catch fish; to them I say, give a dull line a fair trial first, and then make up your mind.
*On small, clear waters. I don't fish reservoirs so cannot comment, but I don't see why it should be any different.