I would mix them honestly. As you know, flat runes are always worse than per level runes in the long run, but start strong. I believe in mixing for this reason. 3 flats, 6 per levels.
[quote=Oberron]I would mix them honestly. As you know, flat runes are always worse than per level runes in the long run, but start strong. I believe in mixing for this reason. 3 flats, 6 per levels.[/quote]
Edit : mana reg. per lvl*