Here is my understanding, with a clear preference for invest (low fees, can deduct more of the contributions):
Prepaid: you CAN use this for private or out of state tuition, the language says you get the average instate VA tuition amount OR your contribution + reasonable/actual rate of return, whichever is less. The "rate of return" has been basically nothing the past few years, which makes me nervous about private or out of state.
Invest: choice of several index, blended, or life cycle funds, including some vanguard options. Small additional management fee. One bonus: each invest combination of account owner/beneficiary/fund choice is treated as a unique contract with a separate deduction up to 4,000/year. So you can deduct much more per year using the invest options compared to prepaid/america/wealth if you plan to put in more than 4k/year per parent/kid.
College America: have to go through brokers. Don't see the logic in paying the additional fees to use American funds.
College wealth: this appears to just be a bank account with 2% interest through BBT or Union first. Fine option if you are close to college age and just want to park it for a couple years, but not good if you are looking for your money to grow.