I have mark ones from
Triang Hornby
Mainline
Replica
Lima
Bachmann
Coopercraft
partial Comet
partial 247
Early Mainline looked good but were slightly out of scale. Lima appeared to be copied from Triang but more of them,, very deep windows, ripe for Cometing
Dimensions for Lima Triang matched Comet, I THINK 247 matched early Mainline so need some extendng.
Bachmann are nicest but most expensive. Replica and late Mainline are next best, only let down by no flush glazing.
Blue Grey set is Bachmann GWR150 converted Triang, next Blue GRey will use my medium pile of Lima with some form of flush glazing when I can work out how.
Coopercraft are a few random preserved.
The late Mainline, the Replicas, a few TH conversions , and some Cometed Lima are to be ran with various Mark 2 sets.
I like consistency within a set if possible