Looking at what I own, I must admit that I buy mostly used, and that is how I voted.
I just tend to like old guns, and in the past, used guns were quite a bit cheaper than new.
My old guns like the 45-70 trapdoor Springfield, the 30-40 Krags, '03 Springfield, CZ-52's, C 96 Mauser and the guns I inherited are all only obtainable used, The rest were available new or used, and I bought them more on a basis of what was available at the time. My used Kel-Tec .380 was purchased because it was a lot cheaper used than the Ruger LCP I was going to buy new. My stainless steel Mini-14 was purchased used from a private sale at a gun show, because it was the same price as the blue steel mini-14 new from a dealer, and it included a nice scope and several extra mags, including 30 round mags. I have purchased several new guns over the years, and will in the future, but it depends on what I want, and what is available at the time.