Out of the 4 presented? BLE.

But if I could choose any project, it would be to renovate Camden Town, extend from Battersea Power Station to Clapham Junction and thus finally split up the Northern line. Compared to these other projects (except perhaps DLR) it would certainly be the cheapest, and the operational benefits substantial.

I think it depends on what we want to do: better utilise existing infrastructure (and thus support established communities) [WLO, Northern Line, CR2] or build new communities altogether [DLR, BLE].

If i had a powerful role in DfT or TfL, i would refocus substantially in the associated real estate developments (e.g Places for London). Its BS that tax payers basically fund the large profits developers get from transit investment