Step 1: Distinguish between absolute area and percentage cover.
- Madhya Pradesh has the largest absolute forest area in India (\(>77{,}000 \, \text{sq. km}\)).
- But the question asks for percentage terms (forest cover as a fraction of total geographical area).
Step 2: States with highest forest % cover.
According to the India State of Forest Report (ISFR):
- Arunachal Pradesh: \(\sim 79\%\) of its geographical area is under forest cover.
- Other Northeastern states like Mizoram, Nagaland, and Manipur also have very high percentages (\(>70\%\)).
- Madhya Pradesh, despite having the maximum forest area, has only about \(25\%-28\%\) of its land under forests.
Step 3: Conclusion.
Hence, in terms of percentage cover:
\[ \boxed{\text{Arunachal Pradesh has the highest forest cover percentage.}} \]