There's a huge difference in what kind of experience I'm looking for between skirmishes and milsim OPs. I appreciate both kinds of events, but I hate it when events advertised as milsim are nothing more than glorfied skirms.
The perfect "mil-sim" experience isn't really centered around any of these things listed in the poll, although all are important.
Milsim is:

Like-minded players who care about more than just "trigger time"

Lots of hiking, not a lot of shooting

A chain of command and objectives that are clear, simple, and realistic

Vehicles, props, and/or actors (usable or not)

Menu # 10: Chili and Macaroni. Also, small bottles of Tabasco.
Milsim is NOT:

Airsofting at paintball fields

Keeping track of your kills and deaths

People talking after they're dead

Terrible impressions (unrealistically mismatched loadouts, long hair, etc...)

Players under 17 (except maybe civilians or child-soldiers...)

Liberal medic rules

M4s in WWII, Thompsons in Afghanistan, or any clear plastic replicas

Blaze orange tips

Team arm bands
I understand that some will say that compromises must be made in order to attract a decent turnout. Orange tips or arm bands aren't the end of the world, but I just don't think they belong in a "mil-sim" environment.
When I was in high school, I used to resent players who advocated age-restricted games. As I grew older, I realized that
as a group, younger players are more trouble than they're worth. Whether it's their shrill voices, rampant hot mic-ing, hacking, or attitude problems, they detract from the overall experience.
I'll be the first to admit that it's nerdy as hell, but the roleplaying aspect of airsoft is something I value a lot. I'm the kind of player who enjoys walking half a mile before engaging the enemy. It makes the contact that much more important and exciting. I'll call myself out if a teammate mistakenly TKs me, even if no enemies were nearby. Heck, my favorite moments airsofting don't even involve me shooting.
(BTW, I voted uniform requirements, because that's the single biggest deal-breaker for me.)