When I saw the thread title, my first thought was "Is there such a thing as an ugly train?" And then I looked at Joe's first 2 links and thought, "Errrrmmmm… Maybe!" Those are two of the most unattractive loco's I've ever set eyes on, I must confess. Sorry, Joe! ;-)

The Hudson, I thought, was rather more handsome naked than in its rather phallic cladding! And since the other one was streamlined in much the same fashion, it also did not grab me. I've no particular suggestion to make. I've never been a trainspotter as such, but loco's have always held a certain fascination, steam & diesel both. The A classes were all handsome beasts. The A1's were all, bar one, rebuilt to A3 (Scotsman) specs, so look very similar, but the A2 Peppercorns were also much the same. The A4's are actually pretty bloomin' ugly without the streamlining. See!

And if you're wondering, yes there was an A5... Sort of... It's actually a pre-Great War tank engine that was classified as a 9N by the GCR. But in general, I think every engine has a certain charm of its own. As I'm not, as a rule, one for favourite or best ("I like this because... and that because.... and..."), I wouldn't care to nominate any one. But unless diesels are considered inadmissible as an answer, I think I should give a shout to the good old Class 55 Deltic! Lovely sound to it as well. Sort of the locomotive equivalent of a Vulcan opening up...