Use Minna no Nihongo if you want deep grammar drills and JLPT focus. Use Genki if you want an all‑in‑one self‑study book with built‑in answers and romaji support. If you’d like, I can also suggest free or low‑cost alternatives (e.g., Tae Kim’s Guide, JapanesePod101’s PDFs, or NHK’s Easy Japanese) that cover similar content legally.