I like metal powder infused filaments, they’re fun to use and whether unprocessed or polished, and can produce prints that look and feel very different from the normal plastics. Not all the metal filaments have these benefits though, there’s a big difference between metal powder filaments and metal colored filaments, and many filaments fall somewhere between. Metal colored filaments can produce great results and are much more affordable, but I’m mostly comparing filaments that have or claim to have actual metal in them.
I’ve had some issues with warping when printing with eSun PETG, which was surprising since I’ve never noticed any warping with PET before that. Since many people seem to be getting warp free prints with eSun PETG, I assumed it might be caused by PETG from the early production runs. So I purchased a new spool, and it does look quite a bit different (rougher texture to the filament). For a test object, I used a fin on my ski pulk as that was one of the prints I was having troubles with. The original was printed as a vase print, with a 1.5mm extrusion width. The retest was done at a 1/3rd scale, also as a vase print.
For all the people who have asked about filaments, here's my list, spread across 8 different posts. This list includes over a hundred filaments, with pictures, measurements, and impressions. All are 1.75mm. Please don't read too much into my opinions, there's a lot of variation in filament and printers, and my opinions apply only to the spools I have on hand. I try to be objective with these opinions, but my preferences and biases affect my opinion, so keep that in mind when browsing this list. Also be aware of the date, some of these filaments may no longer be available, or may be different from what is currently available. I sometimes describe how I use and print some filaments just to provide another data point, it's likely that your optimal setup will be different from mine.