Since people have been asking, here are my personal top 5 EAX games. Of course, this is just my subjective opinion, and everyone is free to post their own list.
1. Battlefield 2 / Battlefield 2142
These two games share the top spot, as the EAX implantation is equally good in both. I've talked about them many times, but the key takeaway is that they use EAX 5.0 and CMSS-3D to their maximum potential, as the developers have worked closely with Creative Labs engineers to ensure that. See here for more details. Positional audio is exceptionally good, and all EAX effects (reverb, occlusion, reflection etc.) are used to their fullest. They also make excellent use of the X-Fi's 128 hardware voices, as seen in this test.
2. Prey (2006)
Another game that makes fantastic use of EAX 5.0 and CMSS-3D, which is especially noticeable because of the unique environments that you get to explore. Due to how gravity works in this game, enemies will often attack you from above, below or anywhere else in 3D space. The game's positional audio reflects this beautifully, especially when using headphones. More info about how the developers used EAX in Prey can be found here.
3. Quake 4
This is another EAX 5.0 title that makes superb use of the tech. In particular, I was impressed with how realistic the in-game explosions sound here, especially when using 5.1 surround speakers. The subwoofer is used to its full potential thanks to EAX PurePath, and positional audio is excellent too. There are also some standout effects, such as when a grenade explodes near you, it will temporarily dull your hearing. A detailed summary of the EAX implementation in Quake 4 can be found here.
4. Thief: Deadly Shadows
This game uses EAX 4.0 in a great way. Every EAX feature gets the spotlight here, including Environment Morphing and Multi-Environments, which help to realistically model the soundstage of the levels. This is particularly important for a stealth game, so the developers handled it with great care (more info here). You will visit castles, cathedrals, caves and clocktowers in this game, and EAX really helps with bringing those places to life. And of course, there's the famous horror-themed mission called "Robbing the Cradle" which definitively needs to be experienced with EAX 4.0 and a nice pair of headphones. Beware of jump scares.
5. Splinter Cell: Chaos Theory
Another stealth game which makes excellent use of EAX 3.0 for its levels. This is evident from the very first mission. For example, try walking into one of the tents there, and listen to the raindrops hitting the fabric. With a good pair of headphones, it sounds like you're actually standing inside that tent in the rain. Furthermore, during that mission EAX is especially noticeable in the caves and inside the lighthouse itself. And it only gets better from there.