If you operate, or plan on operations in the future; it’s best to standardize, on one make of coupler.
Transition cars, are fine, short-term, but long term, in operations, having one standard coupler is best.
What coupler you choose, is up to you, but set the standard before you amass your fleet, so conversion costs are spread over time.
Whenever I purchase a piece of rolling stock, I automatically include the price of the conversion pair of couplers.
When deciding on your coupler of choice; try different ones out, to see which ones work best for you, and consider the experiences of others…then choose.
For the record; I use the Kadee #1’s, and all are body mounted. With over 300 pieces of rolling stock in the inventory, my experience has been very good with them. I have never regretted going with them when Kadee first produced them.