With the weather the way its been today I would be staying on the Rocky stuff,This narrows it down a bit, If your not to familiar with the area.
Pooley Bridge,Roadhead farm to Moordivock would be good using the Bridleway west towards Howtown,This is usually muddy but is worth the decent.
The Ullswater lakeshore Singletrack (from Sandwick) is also good using the climb onto Boredale Hause (my preference) and back over to Martindale is a good loop.
The Borrowdale bash is always a good option but the decent via frith wood has been heavily washed out recently so take care!
Lonscale craggs is ok in the wet but can be exposed/dodgy in windy conditions
The decent from skiddaw carpark via spooney green into keswick is less muddy than the one you have done down latrigg,muddy to start and now rutted!
have a good one! 😉