QR SMU with seating might be ugly on the outside but the cab is really detailed. From download station.
QR RM55 is another really detailed train from the download station.
Electro Transport has really detailed Tangara's and Silver set cabs http://trainzelectrotransport.myfreesites.net/ and they look really good on the outside too.
VR or V/line C class from the Download station again has a really detailed cab.
If you know anyother trains with detailed cabs please comment them below.

I'd recomend SCT class from download station (you may need to edit it).
All trains from Woorybrook station https://worrybrook.weebly.com/
All trains from Australian Trainz division https://www.australiantrainzdivision.com/
NR class liveries from download station.
V/line P class from download station.
QR 2100D/H/F class from download station.
Pacifc National G class from Download station.
Jointed Rail locomotives from freewear section.

Please comment below if you know more.