As the symbol of our nation for flags, insignia, etc, I would absolutely agree that a Phoenix is perfect.

However, personal symbolic sigils would surely already exist in the same way that casting sigils do? I always envisioned Wyndham's symbolic sigil being a lion's face. Funny that.

I have no particular favourite phoenix pic, but I don't like the one facing straight on or the one with a football in the middle of it.

I like the third one from the left on the top row, its nice and simple, clean and you could imagine an even more simple version for people to carve/cut/draw in a hurry.

Casting sigils and 'voting sigils" are entirely separate, although they may often have resemblances. Primarily, voting sigils (which frankly should be called "seals", are an optcome of the AM "Order of Hermes" which is pretty much an outcome on the tribunal structure of the order in 'Mythic Europe'. I'd be inclined to assume that for this setting we are probably looking more at a heraldic type arrangement, which would allow for modification and transformation. And even if it doesn't, I'd be inclined there is a lack of hermetic heralds who would be able to enforce things :)
Personal preference for me as a nation symbol would probably be the 3rd or the 4th version. I can see different branches of government making slight modifications, such as e.g. crossed sword and axe underneath for the military, an ouroboros around it for the mage 'orders', and appropriate versions for the different paladin orders...?

And there's one more :)

I took the liberty of deleting the PDF links at the top of the page that weren't really displaying anything...

Didn't realise they were still there. You should also take the liberty of reducing the Phoenix sigil collection to the only one we're using

Were using a few of them :)
I'd guess that there will by now be multiple versions around. The 3rd and the 7th are likely the most used ones. I'm assuming No 7 is the official seal of government (with different 'tooling' in the claws, depending on which branch, i.e. sword and spear for 'army', staff and circle for the casters, tools of trade for guild seals, etc.). The 3rd is more often used as a decorative symbol...? Easier to make, can be stylised even more, etc.
I'd be inclined to think that the other designs will emerge as individual interpretations...?

The one with tooling would be nice, if not for the tooling. The tooling makes it look a bit tacky. Do not like. I actually like the last two the most.

It is supposed to be a national symbol... They are tacky by definition... :) (The logo is actually taken from one of the OS Quake construction kits, hence the shape and the tools...)

I actually really liked the last one but it was voted down quite a bit. the 2nd from last is really just more elaborate from the alternative official one. IIRC someone decided to simplify this one and came up with the one we are using above :)