When it comes to expressing uncertainty or skepticism, there are a variety of ways to say "had one doubts." Some synonyms include "was skeptical," "questioned," "was unsure," "had reservations," "doubted," "was hesitant," "was wavering," "had misgivings," "was uncertain," and "was suspicious." Depending on the context and tone, any of these alternatives could be a suitable replacement for "had one doubts." Different words may also convey slightly different shades of meaning, so it's important to choose the synonym that best captures the intended message and tone.