、・・・？
Just a simple question... which is stronger, a tiger or a lion?
Literal
Simple question [copula-なんだけど],... tiger [and-と] lion [topic-は] which [subject-が] strong [question-の]?
A casual, curious question with a friendly preamble. 素朴な疑問 (そぼくなぎもん, 'naive/simple question') is a common hedge before asking something potentially silly. なんだけど sets up the question with an explanatory-casual 'it's that...' The actual question uses どっち ('which of two') — the casual form of どちら — and が強い ('is strong'). The explanatory の at the end makes it a soft, curious inquiry rather than a blunt demand.