Paypal Subscription / Recurring Payment API Integration

Need someone who is expert in the Paypal API We are creating a website for a charitable non-profit organization that is wishing to setup a donation page where two choices can be made: 1) They choose which day of the month is best from them to make their payment (select dropdown from 1 - 30) 2) They choose the amount they wish to pay per month (select dropdown from 20.00 - 100.00) This is to be submitted as a RECURRING or SUBSCRIPTION payment and is not a one time donation. We ARE NOT expert in the PayPal API however were expert in web development / php / javascript etc... We would like your 'Expert' advise as to which of the PayPal models will allow for the above idea. For instance: * Paypal Enhanced Recurring Payments * Paypal Payments Standard * Web Payments Standard * Web Payments Pro * Paypal Express There may be more options. We just need YOU to know from previous experience which one is the right one. We do not want you to LEARN using this project. We need an expert who has already done this numerous times in the past. We will require a short list of at least 1 project example where you have used PayPal for this variable subscription model that we can verify. We have already created a PayPal account for this client so are positioned to move forward using their registered PayPal email address. Thank you.