I think it's probably best to judge Robbo and Brewster's two spells separately - Robbo's because circumstances are different and they are 13 years apart, and Brewster's because his availability as a player made such a significant difference in his first period in charge.
Here's how I'd rank them, from last to first:
10. Foran - an absolute catastrophe. Tactically inept, clearly unable to manage a squad and absolutely hopeless at signing players. If we'd ditched him even in March 2017, we would have stayed up. His spell in charge has done this club a huge amount of harm.
9. Brewster's second spell - after an initial strong start things went badly wrong and the last eight months or so were awful. Another manager who struggled tactically and who wound up all the players the wrong way. And giving Andrew Barrowman a three year contract on a big wage?!
8. Baltacha - certainly had some challenges to deal with, given it was our first year in the league. But not even finishing in the bottom half of the Third Division with that squad was a disappointment and too often our style of football was dull as ditchwater.
7. Robbo's second spell - Controversial perhaps, but the bottom line is that we're still only seventh the Championship even though things have certainly improved after a terrible start. Assuming we don't go back up this season, the big test for him will be improving the squad this summer despite a likely reduction in budget.
6. Christie - I have a soft spot for Charlie, who signed some decent players and who often sent out the team to be quite adventurous. And the 2-1 win over Rangers in December 2006 is still one of my favourite ICT moments ever. But he couldn't crack top six.
5. Brewster's first spell - we went from relegation candidates to missing the top six on goal difference in five months. His ability and leadership as a player were undoubtedly huge factors. He also brought in Craig Dargo and established Ian Black (signed by Robbo) in the team.
4. Robbo's first spell - beat Celtic in the cup in his first half-season, won the first division and got us to two cup semi-finals. He had started getting us on the right track for survival when he left for Hearts. Oh, and he signed Darren Dods, who improved our defence about one-hundred fold when he got in the team.
3. Paterson - deserves his legend status because of our rise through the leagues and that incredible win at Celtic Park (and the oft-forgotten win at Tynecastle two years later), along with the reckless attacking football that we played. That said, he had a lot more to work with than most managers in the bottom two divisions did, and couldn't get us over the last hurdle. Not our best manager, but the guy who was managing us when we were the most fun!
2. Hughes - I imagine this will be heavily criticised! If this ranking was entirely on coaching ability he would certainly be top (he turned Carl Tremarco into a footballer!!!) and if it was entirely on transfer market success he would be near the bottom. Bottom line is he took us to third in the league and a Scottish Cup win, feats which may never be repeated - and did so with us playing some pretty sexy football. The fact that his reign started and ended pretty badly shouldn't detract from that.
1. Butcher - obviously left us in pretty acrimonious circumstances, and no-one would suggest that he was a tactical genius. But...he nearly kept us up in 2009 (we were five points adrift when he took over). He got us back up at the first attempt. He turned us into a top six team. The number of quality players he signed was quite remarkable. And man he was good with the media, talking us up all the time.
(puts tin hat on, awaits incoming fire)