In an evaluation of structured data generation using Large Language Models (LLMs), the study compared OpenAI's gpt-3.5-turbo with GPT4All's Mistral and Falcon models across several tasks, including synthetic data creation, data filtering, conversion, and interpretation. The benchmark results showed that while OpenAI's gpt-3.5-turbo excelled in accuracy for non-synthetic data, particularly in content accuracy and data interpretation, GPT4All's Mistral outperformed in generating synthetic data with high type accuracy and schema compliance. Mistral also demonstrated efficiency and cost-effectiveness by running locally without usage charges, unlike OpenAI's model, which is limited by API pricing. Despite being the fastest, Falcon lagged behind in terms of accuracy. The study underscored the potential of open-source models as viable alternatives to commercial solutions, suggesting the use of tools like Guardrails AI to further enhance the accuracy and reliability of LLM outputs.