I just have no ideas for ds this year...
Past hits have been Snap Circuits: http://www.amazon.com/Elenco-Snap-Circuits-SC-300-Physics/dp/B00CIXVIRQ/ref=sr_1_3?ie=UTF8&qid=1386526904&sr=8-3&keywords=snap+circuits
This Chaos Tower was not a hit. Thankfully we had gotten it from freecycle. I think it was too big and ds has a preference for smaller things: http://www.amazon.com/Chaos-81022-Tower/dp/B000XQ8OHW/ref=sr_1_1?ie=UTF8&qid=1386526975&sr=8-1&keywords=chaos+tower
He liked these wooden hydraulic kits but he never built the last one: http://www.amazon.com/Pathfinders-Hydraulic-Machines-Platform-Excavator/dp/B00192MFDS/ref=sr_1_7?ie=UTF8&qid=1386527083&sr=8-7&keywords=hydraulic+wood+toy
He is losing interest in LEGOs but still appreciates the mini kits that come in the bags if they are a cool theme.
He never liked k'nex or erector sets. He doesn't like anything sporty or crafty except, strangely, he liked pixos.