When I play Tank, I put on my hat and drive my speed run train. In the end, so long I don't exceed a certain speed, it'll stay in rails.
Personally I find it more fun to battle 6 enemies at once than 3 each time. (Specially as a DRK).

As a DPS, I like to carry my weight and keep shoveling coal into the furnace to keep the train running. I find it nice to be able to use all my tool kit to the utmost and be rewarded with an amazing performance by clearing everything in a quick and clean fashion.

Maybe its because I have my trustworthy engineer keeping an eye on the temperature and pressure gauges and doing quick and on point maintenances to the machine so its almost always a smooth ride.

Of course, there are moments in which a Train Driver goes too quickly or the coal is not being shoved in at a good enough pace, nvm keeping an eye on the machine's temperature, so it becomes a trainwreck. Be it coming off tracks, exhausting its power, or simply exploding.