I'd rather the system look to fill numbers based on my home BG and then expand outwards to grab randoms from other groups.
1. I'm sure my latency will be better competing against other people from my BG
2. I'd rather see some familiar players than being in one big dump
That is how the system is currently set up, and (imo) it's working out terribly for a number of reasons.
I see very few players who chose their realm based on geophysical location. Mostly because there are EST and PST realms in NYC, Chicago, Phoenix, and LA - realm time is never tied to geophysical location. Geophysical location of datacenters is also something that's not widely advertised - you have to go to third party sites to find that information, as opposed to time zone which is displayed on all official mediums.
Sadly, I get significantly better latencies when connecting to Chicago/NYC battlegrounds, but I rarely get the chance to play games in those datacenters because of how the region-wide battlegroup works.
I'd much rather get instant queues all the time (and horde players get faster queues) with true region-wide BG matchmaking than how it is set up right now. Right now it obviously isn't working going off of what lvl80 players are saying on alliance and horde sides - inconsistent non-bugged queues being a big factor. If so many horde are still experiencing 10+ minute queues, how do you feel when I queue up for a battleground and consistently am not matched into a battleground for 2-3+ minutes during primetime? I wouldn't be surprised if horde would see MUCH faster queues if they took out this "preferred" home battlegroup system, because alliance would be instantly queued into a battleground every time they attempt it. An alliance waiting around in queue, not playing for 3+ minutes just means that the horde queue gets backed up even further with the PvP population imbalance.
Oh and also: how often do you see the same people without region-wide battlegrounds? I'm pretty sure that I never, ever see someone in a battleground ever again after I match with them once. And if it's someone from my own realm, I can easily group up with them and queue as such.
And yet another complaint I have about how the system is currently set up: the battlegrounds are either alliance dominates and steamrolls (because I was matched into a foreign datacenter that favors alliance), or the battlegrounds are horde-dominated and we get steamrolled (because I was matched into a datacenter that favors horde). That is not fun, I want consistent matches that are averaged across all battlegroups.