the strength of consulting companies really depends on the country – in some geographies, companies which are generally considered top notch are not very strong.
Having said that, in general terms the company with the strongest brand out of those that you listed is Oliver Wyman, which at least until few years ago also offered good international opportunities.
I would recommend to also take into consideration the sectors you would like to specialize, if any. OW for example is very strong in the financial sector, less in other segments, SKP is strong in marketing and pricing, etc. For this reason, you may want to take a look on LinkedIn where the alumni of the different companies ended in your relevant geography.