If you do a great deal of shooting, go for the 36. If you need more blam for specific game, or shoot just a dozen times a year, get the 44. it is easier to find accessories and shot in many areas.
Whther a gun is good for target shooting depends on more than caliber. Quality, trigger pull, etc. Most guns used by top target shooters have gone through extensive tuning to smooth the action, lower trigger pull better align the chambers with the barrel etc.
Unless you are terribly serious about competition shooting, I'd go for the 44, simply because you can shoot rats and up to larger game with the 44. I shoot alot a woodchucks with my 44.