So lovely! I sure can relate... I've been riding for over 40 years now and have had my own horses (Morgans) for over 35 years. I am a student of Philippe Karl's Legerete.
So back to Daz Studio.. especially since it looks like you are using Photoshop or another image editing program to add backgrounds and just rendering the horse in Studio, the sky is the limit. I would suggest lighting the horse to its best.
Are you using the total default iray render settings? (or are you using 3DL?) One thing I would check is to make sure you are using Iray MATs for iray rendering and 3DL MATs for 3DL rendering. The Breed Load Alls still use 3DL MATs as that is when they were made/back before iray. I added the Iray MATs later.
So here is a total default iray render of the Arabian using iray MATs. Yeah he is getting a little too much light this way. (But also I have a new monitor /am still getting the calibration tweaked right...) Lots of options to change that.
View attachment 72234
1. Change the value of the base diffuse color. Go to Surfaces tab- pick the horse and then "Coat, then the "Base Color" node. Click on the color and then just make it a darker grey. You might need to mess with this a few times til you get the right amount. You will also need to do the same to the mane and tail.
View attachment 72235
2. Try rotating the horse using General-Tranforms-Y Rotate. Rotate til you get the light falling the way you want.
3. Or rotate the entire camera to get the light falling the way you want, then Y rotate the horse or not to tweak. Here both the camera and the horse are y rotated.
View attachment 72236
4. Add a (fill) spotlight...
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5. Also there are LOADS of great light sets out there that can really make our "Harry" 'pop'....I really love Fabiana's "Theory of Light" sets..
Anyway.. mess around and have fun!!