I enjoyed WoW for a short time at the beginning, but I was playing an older MMO at the time as well, one I always preferred and went back to more. That is Lineage 2 and it's first 4 chronicles, they were the shit (until NC Soft wanted to copy WoW and changed all the rules and design dramatically, the fuckers). So it's fucked now and I'll always miss it, but I understood WoW.
In WoW you had more control and were able to jump, it is has an easy to gage interface and layout, there were many quests and many were different, it has diverse area's, it's dungeons were challenging fun and usually had an interesting boss at the end, the PvP was always full, the cel graphics made no loading hassles (for me anyway), it has many classes, character options, skills, builds, sets, enchants, the mounts, flying, etc. WoW had a lot going for it at the time and I can easily see why it was more popular.
However, while Lineage 2 didn't have as much, it suited me more. Besides preferring the atmosphere, music, general design (besides the revealing armours) and class ideas, it was really fucking difficult and the rules were really punishing, as well as murders waiting everywhere and monster ambushes you had to look out for. I never needed anyone's helping getting anywhere in WoW since I had no struggles at all, but in Lineage 2 you needed it, and it made you want to actually read all the dialogue to find special things and get into a big clan to get the best stuff. So it felt like I achieved something when I did get past a certain point, and besides seeing great execution, this is one of the most important parts in games for me.
Another thing I loved about Lineage 2 was seeing the market place. In WoW you could easily access the warehouse and find what you want to buy, and that's fine. I found it more exciting though looking through peoples custom made stores, looking out for good deals and watching out for tricks. Including they could put their own little message as well, and many people were comedians it seemed. Another thing that was more of a challenge I guess, especially that item drops were a lot more rare.
Also, I reckon the raids were more interesting in Lineage 2, mostly because of the interesting monsters. Nothing in WoW felt as big as fighting Antharas with more than 200 people and you having to time when to come in. Including there was a boss I loved who grinned at everyone on a high ledge playing a creepy melody on a big organ, controlling crazy looking demons, and you had to listen out for when to strike hard.
And one thing about the summoners in Lineage 2 that I've only gotten in one other game is the complete freedom of control over your summon. I mean, it felt like a second player, you used to be able to send it as far as you wanted too, and there were certain tricks you could perform to make grinding easier and more fun. The summons were expensive, but it was worth it.
And of course, overall, I preferred the game play in L2. Despite me saying you had less movement compared to WoW, I enjoyed just clicking where to go next while selecting less skills that mattered more instead of using the same exact barrage of skills on every single damn enemy. I became sick of WoW in no time because I hated selecting the same buttons for every mob. Most MMO's are like that now, and I find watching 'em over and over just makes it more tedious. While in the old Lineage 2 you mostly just selected 1 or 2 with good timing and it would effect the outcome of the fight, including that we were encouraged to use more items at later stages, so it never felt like I was over-doing anything. Well, that wasn't true for everyone of course. Lineage 2 certainly had lots of grinding, but there were ways around it. In fact, I found a way to level with gambling which I thought was funny.
Lineage 2 was never ever perfect and it had loads of problems, but I still feel it had more purpose as an MMO than WoW. I mean, I did it all in WoW; the flying and the raids being the pinnacle, but it became old quick, and so went back to L2 where everything was very risky.