Which software for bookkeeping bureau work

I have recently been getting more clients asking if we can keep their records. This is something I haven't particularly encouraged in the past as the clients tend to make life difficult (not sticking to agreed timetables, bank statements missing etc etc).

However needs must and also I have a client who is purchasing retail franchise outlets (two currently with a target of 6- 8 within 3 years) and he wants my firm to provide a bookkeeping service as it is getting too much for him.

In the past I have used Sage Quickbooks and our own spreadsheets.

However this seems to be an ideal opportunty to review what we use with a view to a) giving the immediate prospect a good service and b) from there offering the service more widely.

So - can I please have your recommendations for software to meet these needs?

Hopefully the products would not require a huge amount of training.

Thanks for any responses.