Which hair dye to pick? L'oreal casting creme praline or medium brown?

I have recently dyed my hair blonde and to cover it up my hair dresser has dyed it brown for me 3 times but the blonde is starting to creep back! i cant afford to go to the hairdressers at the moment so im trying to decide what natural looking brown to use that wont go reddy or too dark ! At the moment i am looking at loreal casting creme gloss in either praline or medium brown? does any one have any experience with these 2 colours or know any other natural looking brown dye that will make my hair nice and glossy and hopefully stick so the blonde does not come back! thanks