Orange Box on 360 is a must even without TF2, but I hope you already played HL2 and Portal
Titanfall is great but keeping a mp-only game in the backlog is not a smart idea imho, especially because there's a better next-gen version and the playerbase will slowly move towards the newer console (there's a 0,0001% chance of seeing Titanfall 2 on 360)
I don't know how is Destiny but there's a demo on the marketplace and a newer version incoming that includes the game, the first 2 expansions and a third one which is not included in the Season Pass. The GonD version is worth it if you're going to buy an Xbox One because it should be cross-buy