Sivaji is basically the typical Shankar story of one man fighting against corruption.  This time he's fighting black money.  The villain is pretty weak.  Not memorable at all.  I don't know how much someone not very familiar with Rajini's Tamil films would enjoy Sivaji, since it is in a similar vein, but on a grander scale (due to Shankar) and even references other Rajini films as well as his superstar status.  Instead of his usual cigarette tricks we get some tricks with a coin and, IIRC, chewing gum.  In that way its sort of a meta-Rajini film.
The songs are good, but most of the picturizations (except Athiradee) were disappointing.   A lot of the comedy is pretty dumb, but I remember some of it being okay.  Shriya has little to do besides being eye candy.  Its also very creepy to see a 50-something Rajini romancing a 20-something Shriya  
 
 I thought Baba was a big mess.  I haven't seen it in a few years, but the story was a mess, and Rajini and Manisha looked unenthused.  Not even AR Rahman brought his A-game to this film.
I didn't see Chandramukhi.