Have you asked your pediatrician if it's OK to switch to whole milk with just a few weeks remaining until 1 year? We moved our daughter a little early, with his consent, because she was way beyond her milestones and again a month early from whole to 1% milk before her 2nd birthday because of her progress.
The formula will be easier as you can make it on demand, but you may lose the opportunity to get him adjusted to the taste difference of the whole milk.
If it were me, and I felt confident that my child was ready, I'd probably elect to do the whole milk. But, my kids were little chunkers, and they were ready to make the move.
Good luck!