Currently looking at bringing my business on my property and need a suitable building to work out of. The general consensus is get a bigger building than you think you need. But with a budget range of around $12,000 it can be limiting. I'll need a minimum off 600 sq ft. Ideally I would like two standard 36" doors and 6 windows. I will need electrical, but I have most of the wire already donated. Insulation won't be needed upfront.

Thoughts on one vs the other?

What are you going to be doing with said workshop? I'd opt for one of those doors to be an overhead roll up, makes moving material and product in and out a whole lot easier.

probably go metal because it would seem stronger. i think the more important part would be to maybe design the building so that you can add on later when needed. like having the larger door be able to be removed and add on to that side of the building when more room or as money allows.

maybe have the whole foundation poured but use some of it as a big porch until you build the rest up.

You get far more sq ft for your money with pole style buildings. Now, building that at wood vs metal I'm not sure as I have no experience with owning a steel structure. If cost were similar, I would go steel. Wood built pole buildings last around 20-25 years around here before the poles rot in the ground. But maybe the new AC2 treated is better, time will tell.

I would mirror the above advise and get an overhead door, a nice big one. 

It also costs very little extra money to go up with pole buildings, I would not go less than 12 feet sidewalls. Gives you room for a gantry if needed, and other options. You can even have room for a short storage loft.

Make sure in your design, you put a fire escape door on opposite side of your primary doors .

I would also look at a dry sprinkler system. I'm going to install sprinklers in everything I build that has water access from here on out. So cheap to buy some pipe and sprinkler heads.

Op you might want to check out prices on quonset type buildings. Looking at the prices of new ones on ebay you could probably get one fairly cheap on inventory clearance.
This guy got his for $1900 new delivered. That was back in 2006 I think. He built his on four foot risers to give room for loft.

Article about building the Carriage House

Also saw a used one in Goshen Indiana.

Quonset Hut Steel 40' x 40' x 17' Fully Enclosed Used Good Condition | eBay