A while back, I posted a comparison between Rift and World of Warcraft. At the time, I'd just started playing Rift after a brief period away from WoW, and wanted to write down what I thought about the two. It's not really meant to be a "rah, rah, go team!" sort of piece, but an honest comparison of my experiences. This is my followup in very much the same vein, but based on my experiences since reaching max-level in two of the classes. I've been raiding extensively, so that will be a big focus.
First, I should point out that my raiding experience in WoW was very limited post-Burning Crusade. The reasons were varied, but primarily I was having fun with friends doing the leveling thing on a new server and then raiding changed and became more machine-like in Wrath, so I never got into it. So, where I talk about WoW raiding, understand that this article talks about WoW in terms of what I saw long ago and what I've read about since.
OK so what's max-level like in Rift? It's just a bit different from WoW. Really the biggest difference is the zone events that happen nearly all the time. When a zone goes active, everyone in the zone gets a quest (and anyone that comes in later, before the final boss appears and is killed, gets the quest when zoning in). Zone events are automatically turned into raids in the sense that you get auto-grouped when taking part in killing invading mobs and such. The mechanics can get somewhat complex, but are never on-par with real raiding, so it feels like a sort of "raiding light" with rewards that are just a step below the Rift equivalent of heroic dungeons in most cases. You can definitely step directly from full zone-event gear into the lower tier of raiding, so you could think of zone events as Rift's LFR-equivalent, gearing-wise.
In WoW, there are usually quest-hubs in expansions that allow max-level players to earn gold and grind faction for gear upgrades at max-level. The same is true in Rift, oddly enough, even though it hasn't had an official expansion yet. Instead, they've added a quest-hub in a patch called Ember Isle. This island has level 52 mobs for the most part (50 is max for players) so it requires players to be decently geared to survive. Once you're up to it, it has daily quests, a long storyline quest chain and the usual rifts and zone events to participate in.
The largest difference in terms of the characters themselves between max-level Rift and WoW is the "planar attunement" system that allows players to continue improving via experience at max-level. Planar attunement will be familiar to anyone who played EverQuest as a sort of variation of that game's "alternate advancement". Planar attunement is not a big game-changer in terms of power-level, but it certainly does contribute, and there are teleport spells available for several major zones from advanced levels of the attunements.
In WoW, the progression from leveling dungeons to heroics has been in flux since heroics were introduced in The Burning Crusade. In TBC, leveling dungeons were required at max-level to get gear appropriate for heroics. In Wrath, that requirement was nominally still there, but heroics were so much easier that no one bothered to gear up in normal dungeons at max-level. In Cataclysm, the gap was widened again and heroics were made much harder than their equivalents in Wrath, and in most cases, harder than their equivalents in TBC. In Mists of Pandaria, WoW will be getting rid of max-level normal dungeons all together, and there will only be heroics.
Rift follows a more complex model that is being simplified in the upcoming 1.7 patch, so let me speak in general terms about what's about to be. When you hit level 50, you can continue to do normal-mode dungeons, but an "expert" tier of dungeons will provide slightly more challenge and give gear appropriate for the first tier of raiding. Meanwhile, "master mode" dungeons will provide further improved gear and currency which can be used to purchase the set pieces for the second (currently top) tier of raiding. Prior to 1.7, expert dungeons were split into a tier 1 and tier 2. Beyond confusion with the raiding tiers, this system didn't change much, since very few players bothered with tier 1, getting a few pieces from normal dungeons and then leaping into tier 2 anyway.
As far as complexity, dungeons in WoW are pretty similar to dungeons in Rift. The both follow the model of having several roughly equivalent bosses separated by plenty of trash mobs in single pulls and AoE groups. Nothing shocking there. The mechanics in Rift differ only in that most "you don't want to be here in a few seconds" type of environment effects have a unified indicator: a red pulsing ring on the ground. This means that you pretty much always know when to get out of ground effects, and rarely confuse them with player abilities.
Raiding in Rift and WoW are roughly similar experiences with the one caveat that Rift raids come in two forms: typical dungeon type raids where they are instanced and "raid rifts" which are semi-instanced. Let me explain what I mean by that: at any given time in any given zone, there are several "planar tears" that can be turned into rift events by any player in the zone. These events can be activated by players of appropriate level for the zone. In max-level zones (of which there are currently 4) there will also be raid tears in random locations. Each tear can be opened into a raid event and when this happens, a new raid tear will open somewhere else. In this way, multiple groups can be doing the same or different raid events in the same zone at the same time. They can interact with each other, but distance usually makes that non-trivial and there's no incentive to do so. Raid tears are also used to open PvP event rifts with substantial PvP rewards, but that's not as popular now as it was at release.
The raid rifts on Ember Isle provide excellent loot which is generally almost as good as the tier 2 raids. However, the loot is very limited, and doing the dungeon raids is required to get a full spectrum of gear.
Dungeon raids are very similar to WoW. The biggest differences are based on the class mechanics differences. Because there are just 4 classes but much more variation within each class than WoW, it's very typical for players not to specialize and for raids to assign players to roles more dynamically than was the case in WoW. Also, because there are 5 spec slots, it's very common for players to have more specialized specs ready to go for raiding. It's even possible to leave zero points in your third talent tree (or "soul") in order to be able to swap it out and gain the intro-abilities of another soul. For example, mages often leave their third soul empty in order to be able to toggle between a small amount of passive raid healing, crowd control or an endurance-boosting damage over time spell. This makes raids a bit more fluid than in WoW, but not to an extent that it really changes the nature of progression.
Raids are fairly large with 11 bosses in the current end-game raid and a companion raid with equivalent gear sporting 4 bosses and 3 mini-bosses. With Cataclysm's underwhelming raid sizes, this is a definite difference.
In terms of mechanics, both games have highly sophisticated and challenging raids. It's more common, it seems to me, to need to stack up in a tight cluster behind a boss in both dungeons and raids in Rift, but then I've only been reading about most of the tier 2 raid bosses, as my guild is still working on the second boss. Certainly the highest-end tier 1 instanced raid (River of Souls) has a lot of this with one boss requiring that everyone stack on him, run out, stack on him, run out, and so forth while another boss requires that everyone stack on him for the final phase. But again, these are small differences.
Rift and WoW are very similar at end-game. Mostly the differences are in the world events, semi-instanced raids and class makeup. Both are enjoyable, but at least for now, Rift retains a substantial amount of "new car smell".