In the past, I have used both. I feel that Strategy did much more for putting weight on than Safechoice.
Safechoise was always fed to my miniatures or fat Mustangs.
The horses always enjoyed these feeds and I've fed both for years with no problems. I really have nothing horrible to say about either, other than Safechoices price increases monthly.
I've since changed to Tribute Solutions feeds and like them much better. Better quality, better results, cheaper, no fillers, pro biodics right in the feed. Solutions 14 for thin or harder keepers and Solutions 10 for the easier keepers or over weight horses.