Anywhere between the high and low mark when the engine is at operating temp should be fine. If engine is cold, basta nearer to the high mark because when the engine gets hot, the oil level goes down (due to the oil circulating throughout the engine).
dagdag ko lang, try to maintain it sa high para kung sakaling nagbabawas man ng oil ang engine mo marami pa itong sapre or reserve bago mag low or maubos ang oil mo.