what level clue scroll gives the best balance between time needed to find clue scroll and reward from clue scroll?

I would think level 2, it's medium level and has some fairly decent rewards. PLUS you don't have to kill anything absurdly difficult.

I think 3. Even though it takes longer to go the clues, it can give very good rewards.

although i do level 3 most of the time level 1's are easy to pickpocket from hams they give good god pages and trimmed magic armor

3's. One's take some time and rarely get anything good from them. Level 3's take 30 minutes to an hour but should always pay 60k+. ALso now with 3rd age 3's are easily the best.