So there are lots of different SRT systems, and depending on what type of device (ascender/descender /or device that does both) you end up getting will dictate which SRT systems you can use and how you ascend or descend.
SRT can be relatively simple, needing only a rope and 2 prusiks (which alpinists typically keep as emergency back ups) or complicated; rope, 1 to 3 ascenders, a descender, maybe a pulley and some bungee to self tend an ascender.
So it kinda comes down to the simpler systems are (typically) less efficient than the more gear intensive systems...but we're hunters so being quiet is a concern, the compactness of all of it, and weight are also concerns. Its a spectrum, everyone has their own opinion on how much gear is too much gear before climbing efficiency reduces the overall efficiency of the hunt.
I would recommend starting with DbRT, if you just learning the ropes (pun intended) it is less efficient as far as the ascent of the tree but it makes you learn some of the basic tree climbing knots (all of which you'll use for other diy project and saddle tweaks), you only need a rope to start learning so its cheap. Most importantly it gives you a knowledge base to work off of and fall back on if you get yourself into a bind in a tree (which is unlikely when just climbing to hunt, but if your gonna be in the middle of the woods by yourself you can only count on yourself and your know how) When I teach friends to climb I start them on double rope and then introduce one new device or variation at a time.
Once you learn the basics you'll have also learned what you like/dislike, what your personal strengths are/what type of climber you are.
I have a buddy that footlocks with prusik for fall protection get to height, if I could footlock worth anything I would too.
If money wasn't an issue, a rope wrench and acsender with a foot loop would be my most gear intensive SRT choice for hunting, but i might just skip the acsender too and go with a large foot loop prusik to reduce metal parts.
...It actually doesn't matter which route you go you'll end up with at least one of everything...hope that helps.
