I put almost as much thought and consideration into my thread as I do my fabric selections. I do quilt on a longarm but I have also used some of these threads for domestic machine quilting. By far I have much more experience in the LA. And I have also used specialty threads to embellish and do hand work.
If you plan on gifting thread it is best to know what types of quilting your recipient wants to do. If they are adventurous and experiment a lot if they like dense quilting or more open quilting, do they like the thread to show or blend into the background, do they like a bit of bling?
I like invisifil which is a 100 wt polyester that acts like silk for doing heavy background fills with lots of back tracking as thread build up doesn't show. I also like to use it for ditch work (as well as invisible monofiliment threads like Superior Monopoly or Glide Essence). Silk acts much the same way but with a more expensive price tag.
I have used metallic in show quilts and was very pleased with the results. I have also seen metallic used in quilts meant to be used. Wonderfil and Superior both make nice metallics.
I prefer trilobal polyester threads over cotton because they don't make any lint and I also like the look of a shiny thread but some people prefer a matte finish. I use mostly 40 wt because I do want my quilting to show. But more and more longarmers are switching to 60 wt which is finer. My thread of choice for trilobal polyester is Glide. But there are many manufacturers. Superior's Magnifico, Isacord, and Sigma embroidery threads are just a few that are out there.
Some quilters are purists and don't want to use anything but natural fibers in their quilt so will only use cotton thread. Personally I think it is a shame to limit yourself to only one kind of thread. But for those that only like cotton there are almost too many choices to list. I have some 12 wt cotton in my stash from Wonderfil that I am just waiting for the right project to use it. A 12 wt cotton would definitely show a lot and I wouldn't recommend it for any quilting that involves backtracking.