I recently made my own tent and ended up using silnylon. Mainly because of the cost as it was my first tent. I did not want to mess up several hundred dollars of cuben material.
In my tent ~88% of the weight was in the fabric. It was a small tent, but the weight (minus stake, poles, and line) using silnylon was 12.7 oz. Out of Sipinnaker it would have been 9.9 oz and out of cuben it would have been 6.8 oz (if I have the correct fabric weights, see below).
Things to consider...
Silnylon ($10/yd) - Wins
Cuben (.6 oz/sq yd) - Wins
Spinnaker (.97 oz/sq yd)
Silnylon (1.35 oz/sq yd)
* let me know if there are better weights to use
Silnylon - Wins, lots of colors to select from
Cuben - see several new colors out
Spinnaker - one color?
Other considerations might be tear strength, puncture strength, waterproofness, stretch, ease to sew, and width of the fabric.