Sorry but I'm going to have to give the nod to Sig. This mostly due to the newer laser cut kits. These things could almost be assembled and held together with just the covering, due to the accurate fits of all the jig tabs. No I'm not suggesting that, just stating the quality of the parts.
I have built many kits from both Mfgr's and agreed you get some bad parts from both. But in these cases both companies were given a call, apologized for the poor condition and directly sent out replacements no questions asked.
Just recently I have built 2 GP Cap 232's and the quality of the wood on some components were questionable (but happily replaced) and the die cutting of the fuse components were ragged and the fit of the jig tabs in their respectivel slots were pittiful, with the slot 2-3 wider than the tab fitting in it. Here too the LG was very fragile. I was warned by reading some reviews but did not take head, my bad.
The second Cap did go together better, but this was due to previous experience. The quality was the same as the first though.
As for expecting both Mfgrs supply every kit with top quality wood with every kit, if this was done then most of these kits would cost far more than the under $100 price tag.
When everything is said and done both kits come out to be very capable aircraft. So what would I recommend? For beginner builder the Sig laser cut kits will work very well. If you don't mind taking extra time to fuss over poorly fitted parts, then GP planes will do well also.
If GP ever decided to change there kits to laser cut components, then they will most likely have top notch kits, at that time I will have to rethink my comments