Capacitor banks or low power rated synchronous generators can also be used...

Assuming that your concern is about the high cost of FACTS. So, much less expensive alternative are distributed FACTS (dFACTS).

Distributed FACTS (DSI,DSR,DSSC etc) is an alternative solution to improve power quality of the Grid, However these devices is not feasible at transmission level.

Which is more effective, comparing FACTS and DFACTS.

from my point of view the the feasibility of D-FACTS is questionable. However we have FACTS device in our System physically. However only US is installed the DSR (distributed series reactor) few month back in there system. so it is very difficult to conclude which one is better....but it seem to be this is future of grid.

Capacitor banks or distributed generation at load end

the quality can be also improve by configuration of DC distribution, DC load and DC generation