Pardew, Monk or Hughes are the only candidates I would even consider. Pardew with everything against him including the fan base still did comfortably well for Newcastle in the first half of the season and his work with Palace has been fantastic.
Hughes has done a ridiculous job, turning an overly defensive side into a side that actually plays football is a hard job when replacing most of the team... when you have most of the same team and have spent sub 10mil total across two seasons that is pretty phenomenal. Not only has he improved their style dramatically they have done better in both seasons than they had managed before under a manager who spent massively more every year(20mil a lone the year Pulis left).
Monk, spent more and didn't change Swansea's style but still impressed. Swansea improved points and league position and he seemed a capable manager with a team willing to adapt and exploit tactics of opposition, change the starting line up to go after certain teams.
Too much of Koeman's credit is coming from simply the lowered expectations of an already solid team losing what people thought were key players. For me they only lost one key player in Lallana and they spent more than enough to replace him. Pretty much Liverpool and Utd WAY overspent on the players they got off Southampton. He still did well and he bought well, but Southampton were a really good team when Poch left and the changes aren't as fundamental as people think, keeping Schneiderlin was key to that though. Losing the central mid rock would have meant bigger and more significant changes.
Chelsea were poor as they limped out of Europe, did buy okay but I still think Drogba and Remy as back up is remarkably weak for a top side. They had the best squad and won the league comfortably without impressing for most of the season. Wenger did nothing special, LVG I think had a very impressive season as he had to turn around the team completely and had a nightmarish injury crisis to start with. Strong season, not brilliant, didn't buy particularly well but who were his choices is questionable. Almost everyone in the team improved over the season, they moved up the table and got into the CL. Job done, just not spectacularly.
Any manager that sucked for half the season or more didn't do well. Fat Sam, Pearson, awful, Pearson for well over half the season and Fat Sam for the second half of the season.