I'm lucky enough to be the custodian of several old motorcycles and this 1927 Triumph is a firm favourite. Bought some eleven years ago at auction, it started up willingly in the car park after I had paid up for it, and has been a reliable friend since.
The '27 Triumph really is one of the easiest flat tank bikes to live with, performance is fair and parts are available. It has that wonderful twenties long and spindly look but is combined with the advances of the latter part of the decade - wired on tyres and decent brakes. My example has been slightly blighted with a tendency to nip up when pushed along, I've always felt that more should be available from it and that it should have the ability to get thrashed a bit harder and take it.