I got this from JapanTackle.com. It has some interesting stuff to consider when trying to decide which brand of spectra you are going to put on your reel.
How to choose PE Braided lines? Which is the best? (Dyneema(R), Spectra(R))
Braided lines of Dyneema and Spectra are all basically the same, Poly-Ethylene based filament lines. It floats because it has 0.97 weight ratio, when water has 1.0 weight ratio. The line is braided with a lot of very thin fibers and it tend to have more body than a single fiber. This is the reason braided lines floats. There are too many braided lines in market, and we should study before we use them.
Most differences of available PE braid lines come from the way of braids, coatings and dying.
Way of braids: 3strands, 4strads, 8 strands, 16 strands
PowerPro, Spiderwire, Fireline and most PE braid line are braided with 4 strands. Each strand is composed of a number of (about 50?) very thin fibers. Braided lines with 4 strands are in the shape of square, but with thin lines it looks round.
There are a few PE braid lines braided with 8 or 16 thinner strands for more smoothness. Those are mostly for offshore jigging for +200-400 feet, rated at more than 40lb-test, and expensive. Those lines tend to have more body, but for jigging, it is not a significant disadvantage. Smoothness is very important because line has always high tension in jigging. I'm spooling 40lb of 8-strand to my jigging reel.
Ripcord lines are braided with 3 strands, and it is flat. It receives more wind than 4-strand line. When lines are twisted, the 3-strand line shows more roughness.
From left, 8-strand, 4-strand, 3-strand
From left, Zenaq-Jigger Trust 40lb, PowerPro 10lb, Ripcord Si 15lb
Coatings: Hard coat, thin coat, non-coat
Most braided line are coated with some kind of abrasion protector because PE lines has much less abrasion resistance than monofilament lines. One of the hardest coating is put on Barkley's Fireline and Spiderwire fusion. Fireline looks like one fiber, but it is braided with 4 strands and then coated with plastic. PowerPro has relatively hard coating, applied to each strand, and you may easily identify the braids of the line. Ripcord Si has thin silicone coating, and it is as soft as non-coated PE line. Ripcord and Spiderwire doesn't have any coating on its surface.
Coating will give the line harder and thinner body. It is good to handle the line in the way of monofilament. The thinner body also receives less affection by wind. But, harder line has more friction with guides in casting, and leads to less casting distance. Though PE material itself doesn't have memory, the hard coating has memory. Softer, less-coated lines require special care in handling to prevent tangles, but cast farther.
Considering the extent of added abrasion protection by coatings and the disadvantage of them, I prefer to use thin-coat line because it casts much farther, and retrieve much smoother. By using mono-leader, I can achieve the abrasion resistance, and don't much need it for main line. Currently, some nylon lines have 20times abrasion resistance to normal mono, and coated braided line may have only the similar resistance of normal nylon line.
Dying: colored or white
It is said that when PE braid lines are died, it gets weaker. However, metered line, colored in different 5 colors by every 20 meter is very useful to know how deep you fish without line counter.
Recommendation
From my experiences, I recommend 8-strands, thin or non-coated line for spinning reel if you will use mono-leader. Ultimate sensitivity line system
For bait casting reels, hard-coated Fireline is still the best. Softer lines will get dig-in troubles.