Also, a big plus for DC motors is that the controllers are simpler. AC motors require a high-power adjustable-frequency inverter.
The only downside of common standard DC motors that I know of is that you have to change the brushes every n years, which I'll gladly take over oil changes. :)
Though, I still tend to gravitate toward the simplest solutions, and in this case, a series-wound brushed motor is about as simple as it gets.
Regular DC motors have heavy and strong magnets (more expensive), but the series-wound motors are just wires (and, FWICT, a bit less efficient).
Regarding brushless, I'm sure they're quieter and require less maintenance, but they still are more complex than the series-wound DC.
I suppose the AC induction motors have their place, but for the DIY crowd, I think many will stick with the basics.