What size (diameter and length of handle) Landing net, would you recommend for fresh water fishing lakes and large rivers, from a sit in kayak like a wilderness Systems Pungo 120 ?
This
http://www.basspro.com/Rubber-Bag-Net/product/104181/
I use a larger than usual trout net. I usually fish for smallmouth bass. A larger trout net works just fine. I also have a long handled net of about the same diameter that I use from my raft.
big fish?
If there are big fish to be landed make sure the hoopsize is big enough. A short handle is all you need. Look at the Frabils with the large hoops.