So I've left it a bit late to post on my own thread creation, but here goes....
Trams/light rail I'd extend the DLR to Dagenham Dock and Thamesmead.
I'd build the West London tram along the Uxbridge corridor.
I'd resurrect the previously planned tram extensions to Sutton and Crystal Palace.
UndergroundI'd rebuild Camden Town station, and split the Northern Line into 2 - Morden to High Barnet via Bank and Battersea to Edgware via Charing X - and I'd extend the Battersea branch to Clapham Junction
I'd extend the Bakerloo Line to Lewisham and truncate it at Queen's Park
I'd commission new trains for the Central, Bakerloo, Jubilee and Waterloo & City line
I'd transfer Metropolitan Amersham & Chesham services over to London Overground (inc Chiltern Aylesbury services)
I'd extend the Metropolitan Line to Watford Junction
I'd convert the Watford DC line to an Underground line using S8 trains made free (See above)
I'd extend the Northern line to Bushey Heath from Edgware and build the full Northern Heights project as was
I'd build a loop at the Brixton end of the Victoria to incorporate Herne Hill
Overground/National RailI'd devolve most suburban rail services to TfL - Southern Metro services, South Western suburban services, South Eastern suburban services, Great Northern suburban services, Chiltern Aylesbury & Wycombe services, Greater Anglia services via Lea Bridge & to Hertford East, GWR Greenford shuttle
I'd implement the suggestions in the South London 'Metroisation' report of improved infrastructure, more frequent services and new rolling stock more akin to S-Stock units (with toilets)
I'd have Thameslink as a separate operation with joint TfL/DfT responsibility
I'd build Crossrail2 in full
I'd convert the Watford DC line to Underground as described above
Buses
I'd convert all but a handful of routes to high-frequency, and change the minimum definition from 5bph to 6bph
I'd introduce a Superloop 3 and maybe even 4 - a whole new network of express routes all over London and adjusting stopping routes accordingly
I'd delay a fully ZE fleet beyond 2030 (No later than 2035) if it meant extra services could be rolled out quicker, but ideally by 2030
I'd get rid of Hail & Ride everywhere but country lanes and the sort
I'd do deals with neighbouring authorities to bring some cross-border routes into the TfL system - albeit with a different brand and colour, but the same fare structure - eg 84 restored to Barnet, 614, 477, 458, 461, 402 restored to Bromley
I'd introduce free electric minibus shuttles around towns and neighbourhoods where conventional bus access was tricky - eg Walthamstow Village
I'd move over to 10 or 15 year depot-based tenders with routes reassigned according to operational efficacy
I'd build a BRT along Purley Way and also along the 472 corridor - using open-boarding articulated buses - and I'd expand the ELT system accordingly too, and convert that to articulated vehicles. I'd also build 'mini BRT's out of big railheads where there are heavy flows, like Brixton, Finsbury Park and Hammersmith
I'd convert suitable high-footfall, shorter-ride routes to either long single decks or articulated vehicles to improve passenger flow and increase frequencies accordingly
I'd introduce tri-axle double decks with a rear staircase onto busy routes with a longer-ride and suitable road layouts
I'd merge TfL enforcement officers into the BTP and expand the unit size to cover buses and the wider transport network
Other stuffThere'll be loads more I'll think of and forget that I'll add accordingly down the line
I'd move back towards 30 mph limits on some main roads, but keep busy thoroughfares in high footfall locations and smaller roads at 20 mph
I'd continue to build cycle lanes and LTNs, but only where they are properly designed and I'd remove ones that aren't suitable
I'd introduce a TfL directly operated boat service from Gravesend to Windsor (in overlapping blocks) with tube-level fares and zonal fare structure and frequent departures - I'd call it 'Waterloop'
I'd abolish peak fares and have a standardised all-day level - I'd also look to harmonise non zone 1-6 fare zones.
How is all this gonna be paid for and delivered?
Building a s*it tonne of new development and the magic money tree. Obvs.