You  should  use  what  they  say  as  a  resource  to  gather  information.

Then  create  your  own  opinion based  on  what  you  think  is  right.

Alternately,  you  can  ask  other  people what  they  think  of  the  situation.

It  could  be  beneficial to  discuss  the  differences &  similarities to  what  Ayumilove  says   vs.  Hellhades.

They  both  are  good  players.

They  both  see  the  game  differently.

They  both  have  reasons on  why  they  do  certain  things.

hellhades seem more practical, ayumi is more for beginer. 

both are good for reference, you should have your own exp and your own setup. 

Ayumilove often offers different scenarios of gear and masteries depending on desired use of the champ.   What they show seems to work for most any level of player, whereas HH is only going to show you hundreds of champs L60 and L16 every which way, so for me he is mostly useless and unrealistic, although his info is probably good just not something I can work with usually.  He has infinite resources (silver, gems, energy, champs, artifacts, etc) so at a whim he can just flip his champs and artifacts and masteries around without blinking.

So my suggestion is go with the best info you are able to use at the time.

I would say the biggest thing to decide is how long you are going to play the game, and how much time are you going to invest in it. These are big deciding factors for me in what I am going to do in the game. If I decide I am going for endgame then I push for that. If I am going to just play and have fun then I do things to that end. Then decide which of the content creators has the best advice for that outcome. Hope this helps. 

Both site is good starting point. They show different aspect of game, but your choice how build your characters. If you see it other good players videos at YT, you will see how many different potential or possibility have this game with just a little changes, in gear,mastery etc.