The notion of prestige is debatable, but assuming it refers to the general perception of the brand, the only two firms with a strong consulting brand between the Big 4 are Deloitte thanks to the acquisition of Monitor (merged also as a brand name) and PwC thanks to the acquisition of Booz (not merged as a brand name), as also mentioned by Julien. Before such acquisition, Deloitte had already a consulting arm. The general perception of the two firms is therefore generally based on the following:
- Booz was generally considered stronger than Monitor;
- Strategy& is branded separated from PwC, while Monitor is not from Deloitte;
- Deloitte did have a consulting arm before the acquisition, while PwC did not.
The first two elements support PwC while the latter Deloitte, so you will probably find people who will consider Strategy&/PwC superior and others that will consider Monitor/Deloitte superior as of today. This in general terms; at local level, things could be perceived differently, and in certain geographies PwC/Strategy would be considered definitely better than Monitor/Deloitte, and the other way round.
At the following link you can also find a comparison between the different firms based on some other criteria. In their review, they put Deloitte as top for consulting, but since the Strategy& brand is separated from PwC, that’s again debatable:
Besides an analysis of prestige, I think it could also be useful for you to consider exit opportunities (in many countries, consultants stay 2-3 years, so that’s not such a remote option even if you are still considering where to go). The simplest thing to analyse that would be to take a look to LinkedIn and check which have been the exit paths for people coming from Strategy& and Monitor Deloitte in your target geography.
Hope this helps,