And I am going to resubscribe for another month. Because I found a little black hole full of fun. Here's how I play my rogue right now:
First, I level to level 10 in the undead starting area. That's actually pretty fun, because this area can absolutely be dangerous. Then I do BGs until level 15. I've posted about a lvl 14 rogue before, so you know that this is fun.
Next, I switch off experience gains and run instances until I have good equipment, most importantly good daggers. DD queues are surprisingly short at this level and I can do non-WoW stuff while waiting. Running those instances is mostly very boring as DD; but it is short enough to be bearable. It's a typical grind to improve your character. I never had a problem with that. Also, you can solo most elites, so I sometime sneak away from the group and kill enemies on my own. The groups rarely care.
Once I have good equipment, I enchant it with cheap enchantments. Then I switch experience gains on again, so that I can enter normal leveling BGs, instead of the twink BGs that have very long wait times and 100% best-in-slot heirloomed and enchanted characters with max profession boni. I do BGs until I hit level 20, which can take quite a while. At 20 I switch off experience gain and do LFDs until I have good equipment ... rinse repeat.
Right now the rogue is level 41 and this is still fun. And that's why I am going to resubscribe for another month.
Please keep in mind that this only works with a few classes, like rogues, feral druids, hunters and disc priests (the shield and penance are very powerful!). Other classes are victims in these BGs without being fully-heirloomed. And, yes, one reason this is fun, is because I can instant-kill every player who is not heirloomed. Of which there are still a few - especially in level 10-25 BGs. Later, at level 40 most players are heirloomed. I guess the new players quit by then.
In combination with being able to stealth, so that I can pick my fights, this makes low-level rogues fun to play in WoW. The heirloomed hero characters actually even add to my enjoyment. Without them it would really be too easy and boring to constantly instant-kill everybody.