My ISP Requirements:
1) Uptime - essential, i can deal with a slower than promised connection as long as it is up, do not purposefully slow it though
2) Capped and Uncapped offerings.
3) Flexibility. Every business of mine has different Internet Access requirements.
4) Support - I want someone I can phone if there is a problem, do not give me a mail address only. I will mail you if I want to, but I want to be to speak to someone. Give me the option, do not decide for me.
5) A sales person by name that I can phone or even mail - I am happy to wait for a sales person on mail, no longer than 2 days.
6) Let me decide on my payment terms - if i do not want a debit order, its because i do not trust you. I will gladly pay in advance if I refuse a debit order.
7) Happy to hear from me when I do make contact, even if it is a problem - at least you know I am still a client of yours and have nnot left you because your opposition has offered me a better package.
8) deliver on your promises.
9) Solve the problem - My ISP states it will get back to me within 48 hours of the time i reported a problem, then they will send me email saying do "x" and let us know, then they will take 48 hours to respond again, etc. and i dont even bother phoning as I do not have time to wait in a call centre que.
10) Do not charge me the world for the above, it doesnt cost many ISPs what they state it costs them, especially not the way their businesses are merged with hosting, DSL offerings, virtual servers, offsite backups etc all adding to the margin.
This is the standard criteria for any product really when it comes to any of business requirements.