I'm of the opinion that there are no good ticketing systems. I've seen a fair few of them (but haven't looked in the last year or two) and I realised that the problem is this: the amount of information you need to store to make a ticketing system really useful is more than people are comfortable putting in. Lightweight ticketing systems are great for small things, but suck for serious work. Heavyweight ticketing systems are a grind to use. Assigning metadata is tedious, remembering workflows is tedious, but if you want more power, you have to do those tasks, regardless of the particular software in use.