I'd say investment in the coming years should be that should be marked as a priority are listed below:

x12 Mercedes-Benz eCitaro's - Connections 4 - Mercs Withdrawn.
x17 Wright Streetdeck FCEV's - Cobalt & Coast 309/310/311 - B9TL's replace older Ex Eyms/Go North West & Lothian B9TL's which would be Withdrawn.
x16 Wright Streetdeck FCEV's - Angel 21 - MH Streetdecks transfer to Hownsgill for Durham Diamond 16/16A/Red Kite Ranger 47.
x16 Wright Streetdeck FCEV's - Tyne Valley Ten - B9TL's replace older Ex Eyms/Go North West & Lothian B9TL's which would be Withdrawn.
x12 Wright Streetdeck FCEV's - Prince Bishops 20 - Streetlites replace Midi Versas which would be Withdrawn.
x13 Wright Streetdeck FCEV's - CityRider 56 - B9TL's replace older Ex Eyms/Go North West & Lothian B9TL's which would be Withdrawn.
x14 Wright Hydroliner Single Deck - Drifter 60/61 - Streetlites & Mercs Withdrawn.

Once these are completed i'd then go towards New Buses for the X-Lines Network with a focus on upgrading Mini/Midibus Services across the region, the then former X-Lines E400MMC's/B5TL's and MH Streetdecks would provide upgrades to the likes of the Crusader 27, East Gateshead Rider 58 and East Gateshead Loop 93/94 along with replacing some on the Ex London B9TL's.