Sounds great!

Also, mixed models will work even when the outcome is missing for some the measurement occasions. In repeated measures ANOVA, the entire case usually has to be discarded if one or more measurements are missing (unless you impute it beforehand).

Thanks Luis and Hans for the informative ideas! Come on guys, add some more justifications that could help me decide!

Partly it's a matter of what software you have available, and what you're comfortable with. You're likely to get a more valid answer with software/test that you're familiar with using and interpreting. The ANOVA may be more limited but if your software has it, you've used it a lot, and you're comfortable working within its assumptions it will be better than the mixed modeling if you have to get new software to do the latter and have never used it before.

That said, as a technique the mixed effects modeling approach is more general and therefore more flexible. If you put in the effort to learn the technique you'll be more likely to use it later, and in different kinds of situations, than the ANOVA. Regardless, for any statistical test you use, you should be knowledgeable about its limitations and assumptions to ensure valid output.

Hope this helps - good luck with it!

Thanks James for your inputs!  I can use one of these: SPSS, SAS or STATA; but which statistical technique is more sound to use in the context I mentioned?? P/s try to help me in clearly reflecting your position with evidences!