DT SWISS or Giant Wheels ?

Please be more specific. Which model wheelsets: with what hubs and what spokes and for what use (commute, race/training, leasure)?

Pretty sure the hubs on Giant wheels are rebadged DTs anyway, but to answer your question: neither, personally. 

2nd Hunt.

My I was looking at a giant defy and I was going to upgrade to a decent set Hunt (disk) wheelset.
In the end I went all in and bought a canyon that came with some loverly DT Swiss hoops, the logic being that now I dont have to look at nice upgrades.....I'll give it a maybe 2 months

I've got a few sets of DT Swiss wheels - all brilliant so I will happily recommend them. I've not tried any of Giant's wheels. 

I guess it partly depends on what your budget is and what the intended use is. I'd also take a look at Hunt wheels - I've not heard any negative reports on them and they seem to deliver a lot more bang for your buck than most other brands http://www.huntbikewheels.com/collections/road-rim-brake-wheels