I run my 3-rail stuff using DCC. I dislike proprietary protocols, for one. Also, when I was making the transition to command control, I had engines from all the major manufacturers that I wanted to keep and run. DCC was the only real option for that. The variety of accessories available for DCC is also pretty amazing. Finally, I like being able to design my own stuff if i want (goes back to the open protocol), like this.
I use an NCE system with the 10 amp booster and a couple of the wireless cabs. Macros are easy to program and are really handy for yard work, and setting up consists is a snap. It's a solid system that just works, and it's great to be able to walk around the house wherever and still control things. I posted a little more detail about my layout here.
I use JMRI for decoder programming and layout control. Here's a screenshot of one of my JMRI panels for this year. Controlling everything from an ipad is pretty cool.
MTH PS3 locos have decent DCC support out of the box, except that I have never been able to read their config on a program track (despite using the recommended programming booster). Other engines I use exclusively ESU decoders, either the Loksound XL or the new Loksound L Select, which is perfectly sized for O gauge stuff (the XL is too big for some engines). Consists are a blast and work great with multiple head units, mid/rear pusher units, mixed PS3/ESU locos, and so on.
