I've been in a Big 4 and a second tier firm. You want advice? The only one I can give you is not which firm you go to but WHAT CLIENT you get to work on. Going to a big 4 and end up spending 3/4 of the year doing public sector and guavamint audit is hell. Going to those small firms i.e. Jan and Piet Chartered accountants working purely on CC's and sole proprietry lacks business exposures. I'm in a second tier firm now (i.e. Grant Thornton, BDO, PKF ect) and don't regret my move. So far I've gained experince and insight in
Media and filming companies
Publishing and advertising
Textile manufacturing
Hospital and medical practices
Financial services
Education and training
Non profit organisations and charities
Airlines
but no IT yet
When I was in one of the B4, I only HAD Guavamint audits! and some public sectors type clients i.e. telkom, transnet, eksom Iskor ect. Find out which department you will get allocated if you decide to join the B4. Experience counts in my books.