It's much more cost efficient to go for the -1 and then HQ. That being said, people with shields on Asura have driven the prices so low your honestly better off just buying. Your looking at around 1mil+ per hexed synth, none of which you can get T2 HQ on. So your looking at an easy 10mil average per -1, add that to the fact that at best you have a 1/4 HQ chance + the cost of eschite ore, just not worth it unfortunately.
After HQing a bunch before shields I noticed I was getting a better HQ proc rate on the 115 synth. But there really is no point to even discuss theories or experiences with HQing these now. Like kao said it’s just not worth it anymore. If you are trying to HQ for yourSelf stick with -1s or making -1s then try HQ. If you’re trying to make profit make final shield first because it’s such a waste of time and Gil now to compete with final shields.