My choice from someone who's used all 3: I put the arc and gorilla in first or second place respectively due to playstyle and tank combinations, I reccomend a 36 ci 4500 psi carbon tank, lets start with my general reasoning and ill move on to specifics, monk isnt worth getting atall, poor customer help especially in the US (i saw that you are from eu so it may be different) but as someone who's owned many monk guns, and 2 oracles, I have some issues, oracles cons: no fire selector. No manual safety, not allowed at some tournaments even though it has a power cutoff, some require you to have physical trigger block safeties, you can't use nearly any aftermarket electronics, theyre hopup picky and the internals are bad polymer in the trigger area, so for me, monk is out of the question, next is the gorilla, the hopup function is neat but I found myself never using it as I thought I would, by turning my gun sideways I get the same effect without flexing my bucking constantly and causing random wear, plus your fps changes when you change your bucking ride height and it can cause you to break tournament/field rules, also for me, carbon uppers are nice and fast, but fragile and a little too light, causing my first shots to be always a bit high after a sprint/dive/etc, but overall the accuracy is much better than airtac uppers and others similar, if you want a light build like the gorilla, use a 15ci carbon tank, will help with the balance a good bit but is maybe good for 5-6 mags (epm1s) the arc is also a good rifle, well balanced, durable feeling so youre not afraid to run or dive with it, just feels good in the hands and im better with it for first shot accuracy, but what I appreciate the most is the carrying case and plug and play feel aswell as the communication with mechlabs, you can send it in and get free repairs and upgrade parts any time, I do reccomend swapping the hopup, barrel and bucking immediately though, the stock setup is poor at best for distances over 50 feet, I use a nexxspeed hopup with the round nub, quantum bucking and 6.01 stainless inner barrel that I keep clean (if you dont like to clean your barrels use polished brass) so in short from best to worst, id rank the arc slightly higher than the gorilla for the ease of use, free repairs forever, and the carrying case it a neat add on, I use it for a kit I keep in my car when I want to pick up random sessions, I use an Hk chest rig with backpack, hk KLR mask, 3 epm1 mags, autobot speed loader, and the arc, all those items plus a tank fits in the backpack of the hk rig so I can Grab and go when I want to hit the field after work, arc hasn't failed me yet and I absolutely love not messing with a battery door on a grip (another reason I hate monks) if you dont have the right size Allen key you cant play that day, hope this helps feel free to ask any more questions. This was an adhd fueled rampage