In 2004 the source code for Shadow Warrior was released. Since 2013 the most up to date source port has been Shadow Warrior Classic Redux. In 2020, a number of new source ports of the game showed up. These will work with both Redux and the free Classic Complete release.

All three ports fixes the invisible mine bug found in Redux.

VoidSW is by the EDuke32 team and is currently in public beta. Builds are available for Windows in the same download as EDuke32. IMO this is the best port for playing with software renderer, but the lack of a FPS limiter in the current build is a big drawback when it comes to playing with Polymost (hardware rendering)

http://dukeworld.com/eduke32/synthesis/latest

WangGDX is part of M210's BuildGDX port. The port integrates the expansions in the episode select and widescreen weapon sprites are bundled. An unique feature for the port is that the palette is given a bluish tint while underwater, similar to other Build games.

There are two downloads available, one for 64-bit Windows users that uses it's own JRE, and one with just the JAR file for operating systems with a Java runtime installed (only x86 and x86-64 systems, other CPU architectures such as ARM are not supported)

https://m210.duke4.net/

Raze is a fork of VoidSW by the developers of GZDoom. It ditches the software renderer, the system requirements are also higher than for the other ports. Raze's signature feature is interpolation of weapon sprites
As with WangGDX widescreen weapon sprites are bundled.

The devs build for MacOS in addition to Windows, so this is a good choice for Mac users not wanting to compile the port themselves

https://github.com/coelckers/Raze/releases

There is also "A Shadow Warrior Port" - http://www.proasm.com
Also has a duke3d port on same site.
I never compared them to these newer ports, and they have not been updated in a while though.
However, I used to use these two all the time, but I recently started test using BuildGDX now (due to supporting more games, and how it handles the expansions).

what do you recommend for OpenGL?

I would use either WangGDX (from BuildGDX) or SWP (proasm.com). Both support openGL and seem to be decent ports. I have not tried VoidSW, and my experience with Raze was short. But seems to work well. Uses a similar startup like GZDoom. I may mess with Raze a bit more, I like the "wad/game list" of GZDoom.

All work well with OpenGL.
Try all three, pick your favorite.

SWP is very outdated (no widescreen support in classic, invisible mines in OpenGL like Redux, no music without mounting a disc image or using an actual CD, tendency to corrupt savefiles) hence why I didn't mention it

That is good to know. I retract my SWP suggestion earlier then. I will move to either BuildGDX or Raze, then, after trying them both out.

It's been over a year since I made this topic. Let's look at what's changed

VoidSW: I'll start off by saying I've not really kept track of this particular port. But it should now keep track of the CVARs you set in the console after closing the port. Still the best choice for classic rendering.
WangGDX: This is something I had failed to mention before, but the physics of the grenades used to be off, which has been fixed in the latest version. Also GDX has added a new renderer (available in all supported games)
Raze: Ok, this is the big one. There's now a Vulkan backend (for modern GPUs) and an OpenGL ES backend (for low end GPUs) Raze also has a new renderer which is currently in testing phase (it can enabled by writing testnewrenderer 1 in the console)

I'm very happy with VoidSW indeed as of nowadays (january 2022), using it with classic rendering, on Linux. I stopped using the Polymer/Polymost renderers a few years ago while using Eduke32, when I discovered that some things would become invisible (most notably messages that were supposed to be read with the night vision goggles).