Dynamite publishes the current Red Sonja since 2005 and, like how Dark Horse does their Conan comics, Dynamite started resetting the mainline comic and relaunching it with a new volume starting at issue 1. Like for Conan the relaunches mark quite different comic books though for Conan they were following the books with jumps in Conan's career timeline. For Red Sonja it's a bit more of a reset because Red Sonja turns out to be a reincarnated champion each of whom live their lives, die and are reborn to become the next champion.

Red Sonja v1 (2005) - This is the longest run and has the most normal stories. Originally it went 49 issues then was ended to make way for Queen Sonja. Because of reader demand they re-continued it. Issue 50 was a special issue of reprinted stories (and the issue is not included in the trade paperbacks). Issues 51-80 are stories of Sonja though later in the run they reset and it is Sonja come back as a vampire (from events in some limited series I guess). So overall this makes for an uneven series.

Red Sonja v2 (2013) - Gail Simone takes over writing for an 18-issue run with a new take on Red Sonja. More filthy-mouthed, hornier, a bit bi-sexual, and the violence seems more graphic. It's the best run of the series though a bit different and maybe that's why it wasn't included in previous Red Sonja bundles until the last one.

Red Sonja v3 (2016) - A short 6-issue run comprising of one story. Unremarkable.

Red Sonja v4 (2016) - 25 issues. This one had a great start with Sonja going through a gateway and ending up in modern day New York. Sonja acclimating to this new world is quite interesting. Unfortunately in issue 12 she goes back to Hykarnia and although some of the modern day characters are still around she never returns to New York and it ends up being the usual sword and sorcery Red Sonja vibe.

Red Sonja v5 (2019) - 28 issues. For the most part this is one very long story. The Emperor of Shadizar invades Hykarnia and Sonja is made Queen of Hykarnia to lead the defense. This is a rather dark comedy vibe with some good military tricks. It continues with Queen Sonja going to Khitai for humanitarian aid, then later the Emperor's son seeking revenge on Sonja. Then a last story arc 10 years later when the former Queen Sonja is needed to save Hykarnia once again.

Overall I rank them:

v2 - great
v5 - really good first story running the first 12 issues, rest of run good enough
v1 - first 49 issues fairly good "traditional" sword and sorcery Red Sonja
v4 - first 11 issues in modern day America is a nice change of pace
v3 - seems more of a place holder story while Dynamite worked on the v4 concept