I main Ad carry/ jungle, and i've recently learned that Shift + RMB is also attack move (idk why i never knew that lol.) I just wanted to get some input from everyone, should i keep using A or shift + RMB? My hand is almost always on shift because of smart cast, but im so use to using A for it. Also the only benefit that i see to it is if you're pretty much alone 1v1 and right next to someone chasing them down. i can see how it would be better there.

A makes it much easier to last hit and attack move minion waves. Can i get some help?

Thank you =)

Preference. I use A->Left click, but it's a holdover from waaaaaaaaay back in the days of Warcraft 2. Just like WASD for FPS games, picked that up back with Doom2. Yes, I'm old.

Do whatever works best for you, or maybe try the other way for a while and see if it gels? You're going to be much better at gauging such things personally than anyone else.

Although I am glad that I listened to the people who said Smartcast All The Things is the WTG.

I've seen people do this on streams, i've tried it out before but never go the hang of it. how does it help you out over just regular last hitting?

Using A helps me out because i just find it easier to actually click the right minion than right clicking.
Also if you accidentally clicked behind the minion you start walking forward, which can very easily get you killed. If you miss click with A, it just attacks the nearest enemy near you. I decided to just keep using A, mainly because im use to it, not because its better.
BUT if you're not using smart cast, id 100% recommend it. SHIFT + (your ability) makes it cast at your cursor, just much faster at spamming your abilities. It might take some getting use to, but im glad i did it.

I use A-LeftClick because I also play Starcraft, which requires quite a bit of micro. I am trying to use shift+rightclick, but it just doesn;t feel right to me. So, in other words, I sacrifice what could be efficiency and accuracy for comfort and habit.

thats the way im feeling about it. im not sure if the minor efficiency boost out weighs comfort and habit.

I dont understand the benefit? or what either shift (rmb) or a (lmb) do?

Shift RMB, is just like a normal move click expt it attacks near by enemies on the way.
A is the same thing, expt you have to hit A, then click where you're going.