The wire you will pull in the conduit is called THHN. There are others approved for use but this is the most common.
You can use EMT (electrical metallic tubing) for a very nice, durable, professional, and in my opinion, safe installation. I used to do it myself before the code change some years ago. It’s just that, being an NEC violation, it won’t pass inspection, around here, anyway. In my area, electrical inspections are not done by building inspectors. They are done by a completely seperate entity, which is certified by the local municipal governments to do electrical inspections on their behalf. We use an entity called the New York Board of Fire Underwriters, which was created by a consortium of fire insurance companies around the year 1900. The inspectors for this agency are specialists in the National Electrical Code, and as such are fairly strict in their interpretations, and are kept up-to-date on changes. After a successful final inspection, we are issued an Underwriter’s Certificate, which we give to the owner, who presents it to the local building department after all other building inspections have been done, in order to get a Certificate of Occupancy (or Certificate of Use) for the barn, after which it is legal to be occupied and used.
We are in the NY Metro area (Long Island) and building/electrical/plumbing codes tend to be rigidly enforced, to the letter of the law, so we do our installations to comply with that. We also don’t usually get paid until we produce an Underwriter’s Certificate, and I have horsey mouths to feed!
Incidentally, in show barns we sometimes put in supplemental fixtures in the stalls with 200 watt bulbs on a timer to “fool” the horses body into not growing a winter coat. These are also used by some to stimulate the estrus cycle in breeding barns.