[EM] Multiple Winner Elections

[Moe St. EverGreen]

What are the best choice(s) of voting system(s)
for a multiple winner election?

I can believe there could be more than one depending
on the type of election.

For instance, we will have a 2 person co-chair in an organization,
where the idea is to balance any opposing factions 
as they will likely occur.

What would be the best form of election?

I know Approval could be used (taking the top two), 
but it seems very easily for a faction to have a strategy
of running multiple candidates.

Cumulative seems a little like overkill, and I'm not sure
how well it stands up against other systems.

I don't see how we could possibly use any form
of Proportional for this.

And I worry that STV is just as bad as IRV.

The other situation is that we will have a large county executive
committee, which we want to elect using some form of PR. 

The idea is that each candidate must choose to run 
either unaffiliated, or as affiliated with one of our 
activist groups or neighborhood groups (affiliation being 
decided by a majority approval of that group).

Whatever the method of election counting, the seats would be filled
in the order of any top winning unaffiliated winners first, 
then the remaining seats would be proportioned out per the total 
support each group received (with affiliated being a group), with the 
seats for each group being filled in order of most support to least 
support.

Since we are a county political party, we won't have parties within
ourself, but we will very likely have factions and neighborhood groups
which will need to have representation.

Please let me know of the best alternative methods we may use, and
if we did use the system above, should we rank the votes, or use
something similar to approval voting, etc., for the actual ballot
and ballot counting.

- Moe.