My shop started life as a 24 x 48 pole barn with dirt floor. When I began to move from a livestock operation to automotive and machining, I converted it into an enclosed 4 bay garage with a concrete floor. Given the ceiling height, we were able to get a backhoe in there and dig a 5' deep pit that I use for oil changing on vehicles and farm equipment. I installed an air line and electricity in the pit before blocking the sides and pouring the slab, so I have lights/electricity and can use pneumatic tools down there. A few years ago, I added a 16 x 20 studded wall annex to the building that is now the primary section for my machine shop.
I'm no builder, but it seems to me for a shop, you're better off with pole barn construction. Given that my original construction was primarily used for equipment storage, I built it with higher than normal floor-to-ceiling span, which was a relatively easy and cost efficient option with a pole barn. I suspect studded wall construction would have been far more expensive to achieve the same clearance and structural stability.
If I had it to build over again, I would change very little. The original build did not anticipate plumbing and electrical supply needs, so I would have incorporated tweaks to allow for that. Both have been conveniently and appropriately added, but it would have been easier if factored into the original construction. Other than that, pole barn construction seems to be ideal for a heavily used shop.
Regards,
Terry