You've listed the options in my order of preference. Recommended candidates are the firms' preferred option so get (a little less) administrative hassle and (slightly) accelerated processing. If your relationships with ex-colleagues are that bad, then I wouldn't bother asking them for recommendations. But if it was just that you didn't work particularly closely before, rest assured that the finders fee will be enough to elicit a resounding reference.Option two will work if you really don't want to be recommended. There are very few HR circles - most of the delays are from partners cancelling out of interviews or not getting round to signing recruitment requests. Recommendations help because it means someone within the consulting practice will be bugging the partner to get a move on. Otherwise, option 2 is a reliable route.Option 3 doesn't strike me as worthwhile - I've been approached by recruiters with Big4 positions before, and none of them convinced me that they have any kind of unique or close relationship with these huge firms. Most of the roles they tell me about, I've already seen advertised for direct hire on this site, and they don't have any more information than is on the Big4 firms' voluminous career websites.