07/08 Arsenal was a brilliant side imo.
Was all doom and gloom as Henry left that summer but Fabregas and Van Persie started to step up as leaders and Hleb was very good for 2/3 of that season, same for Rosicky before he inevitably got injured.
Reminded me of them last season as it started to fall away around March/April but they were a very good watch that season and a fantastic Man. United team that could've easily won the treble once more just about reeled them in.
While it might seem from a United perspective like we just beat them every time we played around that time (and having just checked, we followed our league defeat to them in January 2007 with a run of 19 games in which the record was 13 wins, 4 draws, and 2 defeats, after which they beat us 2-1 in the FA Cup, in March 2015), Arsenal were still a dangerous side for a few seasons after Henry left, not just in 07/08. However, this was the period in which they developed their reputation as bottlers.
Looking back now, there were signs that the wheels might come off for them in 07/08 when Spurs beat them 5-1 in the League Cup semi-final. They did come off about three weeks later, in mid-February, when we stuffed them 4-0 in the FA Cup. They won just one of the next eight league games, drawing with a string of relegation fodder, and crucially losing to both us and Chelsea. That run effectively ended their participation in the title race.
Before that FA Cup game, they were five points clear at the top, and had been top for most of the season. After they lost to us in the league at the end of that run in mid-April, they were nine points behind us, with just four games left. In that time, they were also about five minutes away from reaching the CL semis on away goals, until Liverpool scored twice late on.
They took to long to get going the next season, which left them well short of any title considerations, but after a run of five straight draws (four of which were 0-0), they won seven of their next eight, scored three or more in six of them, and even though we were quite clearly the better team, I remember a lot of the reaction to us only beating them by a single goal at Old Trafford in the first leg of the CL semi-final, being that it wasn't going to be enough to get us through the tie. We of course went on to beat them 3-1 at the Emirates, and Chelsea followed that by beating them 4-1 in the league (which actually happened to be their first league defeat since mid-late November).
In 09/10, they once again found themselves in the title race. As with 07/08, there were signs that wheels might come off after they followed a win against Bolton, that saw them to climb (temporarily) into second, by getting knocked out of the FA Cup by Stoke, drawing with Villa, and losing back to back games to us and Chelsea in the league. They kept within touching distance though, and with five games left were third, three points behind Chelsea in first, and only one point behind us, with a game in hand. They subsequently failed to win any of the next four, losing three of them, and finished 11 points behind Chelsea and 10 behind us.
A similar story in 10/11. With six games left they were six points behind us in second, after a draw with Liverpool. They'd win just one of the last six games (ironically, against us), losing three, and ended up fourth. City, who were seven points behind Arsenal with six to go, ended up finishing three points clear of them. This was also the season that they lost the League Cup final to Birmingham City, who would be relegated from the Premier League (yet to return) later that season.
They were actually top for a good stretch of 2013/14 too, but then they lost 5-1 to Liverpool, starting a run of just two wins from nine, that also included a 6-0 defeat at Chelsea and a 3-0 defeat at Everton, and they ended up fourth (although they won the FA Cup that season so it doesn't meet the criteria for this thread).