Could you explain what the differences between
1) Ideal Easy ABN/Amro
2) Ideal Lite
3) ING iDEAL Advanced, Rabobank iDEAL Professional or ABN iDEAL Zelfbouw.
Every bank that offers iDeal, sells it together with a certain level of service. These packages can differ in price, support level, etc. Most cheaper packages do not provide direct feedback, so your web application cannot immediately 'know' if the payment succeeded or not.
I'm not going to compare the different packages for you, because I'm sure you can do that yourself. Most banks have specs on their websites, like this one and this one. If I'm not mistaken, you always need a bank account with the bank whose iDeal service you choose, so for instance if you choose Rabobank iDEAL Professional, the money you receive will be put in a Rabobank account. You'll just have to see which bank has the best offer to match your needs and budget.