Absolute snake, most of that era turned out to be bad eggs and he was the worst.
Van Persie - Left after his first great season, in that fashion and to the enemy despite years of being given tutelage for spending time on the treatment table. Fergie/Mourinho would have shipped him off long before.
Cesc- Great PR and self-awareness. I'll cut him some slack because he was great and could have left from 2006 onwards and stuck around for the project for 5 more years. What he's managed to mostly cover-up is that he went on strike and we got peanuts for him (35m pounds).
Adebayor- I think better than a lot of people give him credit for but a terrible personality and badly advised. Would have been stuck in mid-table Ligue 1 without Wenger. One of Wenger's last great buys turned a 2m Monaco reject into a player who scored 100 league goals in England and went on to represent Madrid.
Nasri- Asked for too much money, ran down his contract, and gave exactly 7-8 months of above-average form.
Song- Looked truly awful early on and many will remember that famous Fulham game. Something must have happened behind the scenes in how he went to Barcelona for a knockdown 14-15m when he had many years left on his contract.
Hleb- Another that was persevered with for a while before he became better, and then fucked off after his first breakthrough season.
Gallas- Defeatist personality, training ground conflicts and ended up at the scum.
Wenger brought people back like Flamini/Sol so even though he had possibilities to bring back people like Cesc, Hleb he chose not too.