Ideal Dell Laptops for External GPUs

Ideally you want a system that still has a high-performance CPU to minimize any GPU bottlenecking. But systems with high-end CPUs also tend to come with higher-end GPUs.  If you don't want to spend money on a built-in GPU, then one option would be the XPS 15.  The current model is the 9510, but everything I'm about to say applies to the earlier 9550, 9560, 9570, 7590, and 9500 generations.  The XPS 15 models come with 45W Intel Core H Series CPUs instead of the more common 15W low-power U and G Series CPUs, and they can be configured with only an Intel GPU if you don't want a built-in NVIDIA GPU.  And from the 9550 onward, they have included Thunderbolt as standard.  One consideration here is that the XPS 15 models are designed to still be fairly thin and light, which means they don't have huge cooling solutions and therefore can experience thermal throttling under sustained heavy load, but if you'll have your GPU load on an eGPU, that may not be an issue.  If that's a concern though, the systems that have larger cooling systems that can reduce/avoid throttling are also going to be larger and heavier, and will typically include their own internal GPUs that you might not want.  These would be systems in the Inspiron Gaming and Alienware lines, and technically the Precision 7000 Series lineup, but I wouldn't recommend that option for your use case.