38/357 would be the most economical to load , smaller (cheaper) bullet , less powder as well.
Accuracy wise all capable, at the club I go to most use 38/357 for gallery rifle , some use 44mag down loaded to 44 special velocities so as to not exceed range safety limits ( same with 357 magnum- downloaded) .
Personally I like the 45long Colt , lovely round to use ,but if I was competing in a ' moving' competition it would be 38/357.
With regards loading gear a lee turret press would be a good start , start loading individual rounds and once confident then use the semi auto feature of it .if you find you are shooting a lot hen a progressive press is the way to go,however they can throw a wobbly if you run out of primers or powder.
Re books to get- one or more reloading guides form Sierra or other manufacturers,I always recccomend Hand loading for competition by glen zediker,it primarily applies to rifle cartridges but is applicable to reloading in general.
Not forgetting you tube,whichhas loads of videos on it as well.
Hope this helps
James