At the low end (ie. my computer builds for the average user) I want a board with a heatsink on the VRMs. A decent selection of video out ports is good, as well as a decent number of backplate USB ports. 4 DIMM slots for mATX minimum. I tend to avoid the lowest tier mobo chipset.
For my own PC, I tend to go for boards with more power stages as well. Video out backplate ports aren't so important as I imagine I'll have some kind of discrete GPU in my PC till the day I die.
We're on the same wavelength with that. After 2005 I was sort of committed to "second-tier" overclocking, trying to do as much as I could without (a) water-cooling and (b) pushing the VCORE beyond Intel-advised limits. Whether I could actually see it this way or I just imagined it so, I was greedy for as much phase-power design as I could get, and I paid attention to board-maker's assertions about VRMs and Mosfets.
I have built systems with Intel, Gigabyte, Abit, Supermicro and EVGA motherboards, but beginning with the ASUS Striker board (Conroe and Kentsfield processors), I became enamored of their BIOS design and boards. I was influenced by ASUS''s assertions of building to a "MIL-spec" -- first mentioned with the STriker and then again with their Sabertooth line.
I also thought their warranty support and RMA reliability seemed stellar. What happens as these judgments accumulate is a tendency to decline trying boards of other manufacture. It was the same with RAM choices: I had tried Corsair, Crucial and Mushkin -- but soon settled on G.SKILL -- again impressed with a personal level of tech-support and reliability for their OC models.
I always make myself comfortable with my overkill decisions, but I tend to choose models in the ASUS midrange and below the Maximus price and features level.
If I'm building systems every year, I would choose low-end motherboards. But if I build a new system every three to seven years, it becomes a hobbyist's planning and design effort, and saving money takes a back seat in my decisions.