I second d a’s picks. Eli Shekhter’s books are indeed amazing, dunno if it substitutes non-Jewish ones (especially the writing-style), but they’re good. However, it’s been a while since he wrote anything. If you want something different (and more on a professional level) you might wanna try Meir Uri Gottesman’s books. While I enjoyed The Will, I felt it was very immature and unrealistic and while I love Yair Weinstock’s way of writing, I think his plots are stupid and unrealistic.
Bottom line: No Frum novel will replace a good non-Jewish book in all aspects. It will be missing something. Research is something that needs much improvement.