Another option is to find minis on thingiverse.com open the stl files in Blender, and export images to use.
If you are unfamiliar with either, thingiverse is a site for free 3d models, Blender is a free, powerful 3d editing software.
Now that's an idea I hadn't thought about!
How would you go about having a front and back images?
An annoying problem I ran into while playing around with Heroforge is that there is no shortcut to rotate the model exactly 180 degrees on the x- and y-axis. That means it will be quite difficult to get an exact matching front-and-back shot of the model. I'm quite perfectionist in that regard, so it triggers me
I've never used them. They look better though than using the paper ones with white backgrounds.
I've got a good trick for the paper ones with white backgrounds. If you outline them with a permanent black marker, then cut them out as much as possible, they actually look pretty good on the table. Best if they're printed on gloss paper too (or sprayed with gloss sealant).
Providing you're printing them yourself, I've got a better trick:
Open the image in your favourite image processor software. Photoshop, Gimp, Krita, etc
Create a new layer
Copy the image to the new layer and fill it with black (only the copy on the new layer)
Color select that now black image
Hit grow and give it as many pixels as you want
Now go to fill and fill the selection with black.
Move this layer below the original one.
Now create a new transparent layer above the black figure
Change to the original image layer
Select the white background and cut it (if it's a png if not you need to copy to a transparent layer before being able to do so.)
Now copy and paste that image in the layer below
while still selected fill that with white. Any holes you see that were created by cutting out the white have to be filled by hand.
Once the white is finished you can proceed to export your image, now it has a thick black outline.