Play a game like Mafia and you may just revise your statement.
When I have do a lot of slow driving around in Mafia, I appreciate aniso more than AA. Which means to say I appreciate aniso more than AA in a game like Mafia. Not being able to see the white dividing lines on the road is more disturbing than aliasing.
Of course, AA is still preferred but AA + aniso in Mafia is a no go with a GF4Ti4600 due to performance reasons. I haven't checked which results in a greater performance hit (various AA vs various aniso) but I didn't bother because I felt that aniso was more important in Mafia to me than AA.
Actually, I finished Mafia on my gf4ti4600 and I played it with Quincunx AA+Aniso 8x all the way through and it was very playable (around 20-25fps on car and about 30-50fps on foot). I have to disagree though, when playing with Aniso 8x enabled (just that), that didn't do much difference to the overall IQ (although less shimmering was obvious), but when playing with AA enabled, I could see almost no jaggies anywhere, which counts more for me than "removing some of the bluriness far away". Definetly, a combination of both at the highest quality is the most preferable way to play, but unless you own a R9700pro, no card can provide you with a fluid enough experience for that.
A combination of AA & Aniso is the way to go, using them seperately kinda ruins the experience. One technique accounts for the faults of the other and vice versa.
edit:
I can definetly see your point with these pics, but let's be fair here: while you're playing the game, it's not
THAT noticable and doesn't distract from the overall IQ, while seeing the bumper of your car jagged as hell does indeed destroy it (at least for me it does).
Conclusion: A combination of AA & Aniso at the highest settings is the way to go and does indeed have a great impact on the overall IQ, but when using Aniso & AA seperately (either that or that), I prefer to use AA.
P.S
Keep in mind that the impact Aniso has on Mafia is quite substantial, while the impact it has on other games is much less visible (in Q3A for instance, it's only good for taking pics).