To date, no studies have provided a comprehensive overview comparing ChatGPT, Bard, Llama, Ernie, and Grok within a single paper. For clarity, this paper refers to ChatGPT 3.5 and ChatGPT 4.0 collectively as \"ChatGPT\", and similar amalgamations are applied to other chatbots. Specific versions, such as ChatGPT 3.5 or Bard's different iterations, are discussed in Section 4. Bing Chat is excluded from this study due to its reliance on the same underlying technology, GPT 4, as ChatGPT 4. The term \"Llama\" is uniformly used to prevent confusion. Although prior studies have compared subsets of these chatbots, none have encompassed all five in an unified analysis. [PERSON] et al. [7] compared ChatGPT, Bard, and Bing in the context of medical physiology but did not include Ernie, Llama, or Grok. Other studies have similarly focused on limited aspects or subsets of these technologies [8; 9; 10; 11]. This study aims to fill the gap in the literature by providing a detailed comparative analysis of ChatGPT, Bard, Llama, Ernie, and Grok, thus exploring their applications across various fields. Consequently, this study aims to answer the followings research questions:  
1. How do the unique features, target audiences, and potential future developments of ChatGPT, Bard, Llama, Ernie, and Grok compare, and what insights can be drawn from this analysis to guide the selection and application of AI chatbots in various domains?
2. What are the key ethical concerns, cybersecurity risks, and limitations associated with the use of AI chatbots, and how can these challenges be addressed to ensure the responsible development and deployment of these technologies?
3. Considering the differentiated strengths and weaknesses of each AI chatbot across various domains, such as medicine, technology, education, ethics, humanities, and writing, what are the implications for the context-dependent utility of these models, and how can this knowledge inform future research and practice in the field of AI language models?  
By addressing these research questions, this study aims to provide a comprehensive review and analysis of the current state and future potential of AI chatbots, thus contributing to the ongoing scholarly dialogue and informing the responsible development and application of these technologies in diverse global contexts. Hence, the unique contributions of this study include the following:  
1. Conducting a comprehensive comparative analysis of five leading AI chatbots--ChatGPT, Bard, Llama, Ernie, and Grok--across multiple domains, including medicine, technology, education, ethics, humanities, and general human interaction, based on a systematic review of 28 scholarly articles using evaluation criteria such as performance metrics, scope of knowledge, computational efficiency, and domain expertise rating.
2. Identifying and synthesising the specific strengths, weaknesses, and contextual applications of each chatbot based on the findings from the reviewed literature, thus providing a nuanced and evidence-based understanding of their utility and limitations in various practical scenarios.  
Figure 1: Timeline of language model and chatbot development.  
3. Highlighting the rapid evolution of AI technologies and the need for continuous, updated evaluations while addressing critical issues such as data privacy, security, potential biases, inconsistencies in responses, and the need for clear guidelines and regulations to ensure the ethical deployment of AI language models.