i would say GGL is the most secure and best out there, with how much you can customize your settings in there ingame UI.
There healing settings for healing classes are miles ahead of any other compition out there.
They have some very advanced logic that NO other pixel rotation have out there to handle totems and explosives orbs automatic with targeting them.
That i havent seen any other devs be avaible to solve or do.
HyperELK seems to support most classes out of the box, but there PvE rotations in m+ when testing a trial period seems to lack and there devs arent as experience in PvE and PvP as GGLs devs are.
None of HyperELKs devs seems to be multi ranked glad or even R1 players for there profiles.
There PvP profiles lack advanced logic and only seem to have support for PvP abilitys to be used on cooldown, no advanced settings for interrupts in PvP.
For there PvE they say its impossible to make a pixelbot target explosives orbs or totems, even that GGL have had it for years, which shows a bit of lack of knowledge or skills from them.
There PvE profiles dosent seem to be close to the dps as GGL have in m+ and mythic raiding (remember i only tested HyperELK for 3 days, where i did 1x mythic SOD raid (10/10) and 4x Mythic+ 20 keys) and the 4 rotations i tested was behind in DPS. Might have been just these 4 (the seem to support all 36 speccs and some said they where moving from v2 to v3 of HyperELK, that cause problems also)
HyperELK is also new and havent been targeted yet, so so far they are undetected but with how new it is, its security is hard to say how it is vs GGL thats been out since TBC/WOTLK with 0 bans.
Since my account is expensive and i cant lose it, security for me is number 1 priority and since i raid in a CE guild i require to have speccs and classes that perform 97+ for securing a raid spot.
So far the ones i have tested only GGL so far have perform this good for me.
For new members GGL is lacking autobind, but they say its on the way and new big update is comming.
The cost to pay someone to set GGL up can be a bit expensive and it will take a bit of time to do it yourself first time, but as soon you have done it few times it faster, but its rough start.
Edit: Also something that is concerning is that HyperELK seems to be based of the old scamming pixel bot Pixelmagic -