I used to use a WAGN service train from Stoke Newington to Liverpool
St, which was, on the whole, pretty reliable.

Now a few years later, having tried to use the same service a couple
of stops up at Bruce Grove (now I believe run by One) it's just
totally unreliable/impossible. In my experience, trains have never
arrived on time, northbound or southbound, & are often cancelled with
no explanation, or even an announcement to tell you that the late
train you're waiting for, ain't even coming!

In the years between, I used a WAGN service from Palmers Green to
Finsbury Park. Best overground service ever in my opinion. Never
suffered a late train, & the fast morning service direct to Finsbury
Park was excellent!