I don't know where you live, as you limit those who are able to view your profile however, going by Great British Pounds, the combo of your two choices would be £47.98, which is £7.01 less dearer than the Bastion set at £54.99.
Also, the Bastion set has a slightly higher PPP (Price per Piece) at 9.1p.
The other two sets combined (129 + 455 = 584) is 8.2p per brick — lower is better.
On the other hand, the Bastion model is often mentioned to be the most desirable set out of the LEGO Overwatch theme and that it feels like a proper display piece, especially with the robot being a shy over 10 inches tall.
If you would like my humble opinion? Get this one!
Ooh, I am looking forward to seeing the whole gang together!