Simon's on the money.
In my experience I have found generally sails with most crossply last longer, but are heavier to manouver.
NP sails feel powerful and light, but seem a bit fragile (ie they crinkle quickly). Tushingham sails have better twist off, and seem to deliver less grunt (so you use a bigger size) but have a wider wind range and seem more robust (heavier material ?).
As one saleman quoted, NP feels like a V8 (good torque to get going, narrow rev range), Tushingham feel like a turbo (poor torque till it winds up, but wider rev range)
Up to you whether you prefer to sail a smaller, lighter, "high performance" sail or a larger, heavier sail that has a wider wind range and may last longer before you crash through it.
Can't speak for other brands - no experience.