Honestly, the first season was the worst, because it was such a toxic mess that it was so hopeless. This season sucked, but there's hope there, and other seasons were tough to suffer through, but watching POS and others just suck out and quit was just awful.
The thing with that season is the descent began with a whole bunch of injuries which kind of justified the result at the time in my mind. Then when it became evident they weren't going to accomplish anything there was the excitement of a potential first overall pick. I watched little down the stretch but I was okay with it "for the better good".
This year was a kick to the junk in that we expected better and actually got worse and the novelty of a first overall pick has worn off. This was emphasized by the fact that the Oilers really did not suffer a significant injury all year other than Sam Gagner, and even he only missed 15 games. As a result, this year is the first year that I started feeling like this rebuild won't end up bearing fruit.
As such, this year hurts the most. My rankings would be:
1. 2013-14: enough said earlier
2. 2006-07: Pronger trade demand. Smyth trade. First place at Christmas before imploding and losing everything post trade deadline. Devastating turn of events from playing Game 7 the prior season.
3. 2012-13: Shortened season. Kids were hot during the lockout, creating high expectations, but team never really took off and choked down the stretch
4. 2009-10: Horrible season buoyed by the excitement of a potential first overall. Had a little hope that it was a result of injuries moreso than the skill of the team. Was proven wrong.
5. 2008-09: MacT era coming to an end
6. 2011-12: Fail for Nail, was settled in for the long rebuild so didn't have much expectations and enjoyed RNH fantastic rookie season
7. 2010-11: Rookie seasons for HOPE. Loved watching the potential and had low expectations which were basically met.
8. 2007-08: Nice late push by overachieving team that just had it's guts ripped out the year before. I fully enjoyed watching this season with the rookies of the first phase of rebuild. Too bad, it didn't amount to much.