I'm interested in working in operations consulting and was wondering if firms such as Deloitte and ACN have a good reputation in this practice area?

In my experience ACN are well represented in operations at many banks working from departmental TOM level downwards to simple process flow design and capture.

Deloitte and EY will only do Ops work at a more senior level as their cost structure precludes having junior staff sit there drawing up process flows and swimlanes.

If you really want to do Operations improvement I'd suggest niche consultancies rather than big4