Online accounting system for an accountancy practice

Do any of you accountants in practice use any of the online accounting systems as an alternative to Sage etc?

I am looking for such a system which should have the at least the following features:

1. Multi client - i e allow you to do the books for multiple clients
2. Purchase and sales ledger
3. Bank payments and receipts and reconciliations
4. Generate the basic reports that Sage does (Transaction history in various ledgers etc).
5. Affordable and easy to use.

Any advice gratefully awaited