LM Studio has been around longer. I’ve used it since three years ago. I’d also agree it is generally a better beginner choice then and now.

Unsloth Studio is more featureful (well integrated tool calling, web search, and code execution being headline features), and comes from the people consistently making some of the best GGUF quants of all popular models. It also is well documented, easy to setup, and also has good fine-tuning support.

LM Studio isn't free/libre/open source software, which misses the point of using open weights and open source LLMs in the first place.