Polish your rock paper scissors game, remember the patterns, Saber first playthrough, then archer, then Caster (order of difficulty, if you try to tackle the game with Caster for the first time you're gonna cry, she is the weakest at the start and leans heavily as the strongest by the end), FeMC is moe
I'll try to keep this relatively short even if that might mean I don't get to convey everything.
I enjoy Bell's obsession towards a goal (hence the skill he awakened), his altruism even when he isn't in the best of situations himself, and his willingness to still dream big in the face of constant harsh realities thrown his way. His struggle to survive and grow after being left with virtually nothing at such a young age is probably where it truly starts for me. Some aspects of how he turned out this way I won't get into because they are novel spoilers, but Bell manages to have a lot of the traits I enjoy in various different main characters but doesn't have any of the qualities that grate on me after a while. A lot of the other light novel protagonists manage to piss me off with a fatal flaw or two while Bell largely avoids that for me. That is probably what stands out to me.
With Bell, it is largely about the journey and execution for me as opposed to him being this uber unique character that you point to as a trend setter or genre breaker.