Well... Solomon asked for wisdom, and God granted him this wish and gave him many material blessings as well. So I guess I would be a fool not to ask for wisdom.
But the 3 things I pray for constantly are Repentance, Humility, and Perseverance. I reason that as long as I have a repentant heart, a humble spirit, and a persevering attitude then I will always be growing and developing spiritually. I guess I pray for these things so often because I feel like I don't even come close to possessing them. Perhaps I never will.
"Lord Jesus Christ, Son of God, Have mercy on me a sinner."