This chair had been getting great reviews for a reason.. it's compact, light weight, and comfortable. It is pretty expensive ($112CAD) but it comes with a 5 year warranty so i figure a comfortable camp chair for $20 a year is pretty reasonable. Its small enough to fit pretty well anywhere in a kayak or bag. Even if you overload your boat its small enough to fit between your legs or under/behind your seat.
There is a downside however, I have been using it on possibly the worst ground for it.. soft, slopey, fine-silt river bank. With nothing on the legs it sinks into the ground and puts undue pressure on the pole connectors. Therefore, I also picked up one of the Helinox Ground Sheets (size small) which has completely solved the problem. On the super soft terrain, the ground sheet not only stops the legs from sinking, but you can build up the ground underneath it to create a level platform pretty easily. It also fits into the carrying case really well. It is pretty expensive for a mesh sheet ($35CAD) but the corners are reinforced and it's really well built. If you're planning on using the chair one for river camping I highly recommend investing in the ground sheet.