I see next to no value in the Dorans items except for the ring, and maybe the shield in certain situations.
I mean like people could disagree, but this is my personal reasoning/preference.
Dorans Ring - Very useful. Hands down a must in nearly all AP mid champions. No exceptions, self-explanatory.
Dorans Blade - Worthless. Since they nerfed it to +3HP/auto and decreased longsword to 360 gold, I don't see it as viable as a sustain build for ADCs, especially since it doesn't build into anything. I don't really feel like doing exact math, but when you think about it, it doesn't provide as much sustain as longsword + 3 red pots. A red pot regens 150HP each I believe, meaning 3 red pots give 450HP regen. In order to get the same regen from a blade means you would need at least 100+ autoes or something like that. Even if you autoed away and pushed your lane, considering your champion attack speed, you still won't regen as fast as popping a red pot. When considering trades, the +3HP gained per auto will still not regen you as fast as a red pot. The +80HP is nifty, but easily becomes negligible. Best of all, if you're behind, you could just simply buy 3 longswords (or 4 if you're playing like Ezreal or something) since it could build into LW, BOTRK, BT, TF, etc whereas buying a second (or even 3rd) dorans sword will provide you the stats/sustain, but sacrifices your build. I usually buy 3 longswords if I can't afford a BF straight away since even though it gives you less AD, it still provides comparable stats at a cheaper price.
I mean like this is easily arguable depending on preference, but I always personally buy 2-3 red pots and 1-2 mana pots on each back depending on how much gold I have left over. Just purchasing those pots easily made their worth back in gold and some more. Saved my life countless times, and provided me the regen to bait kills when they try to chase or when I juke out and decide to go back in. At least once a game it's done either one of the two for me.
Dorans Shield - I don't like this item in the slightest, never bought it before in my life. However, I can see the usefulness in it on certain champions for the regen/HP purposes but this is probably strictly based on preference.
Edit: Oh, and for anybody saying the regen on doran's shield is broken, it's really not considering the fact they do not stack and you can only purchase 1 pot and the +10HP/5 (I forget what exactly). If they ever start dorans shield + 1 pot, I just go balls to the wall aggressive level 1 since I usually start with at least 3 red pots. All you need to do is establish early lane dominance and the only thing they can do for regen is to sit behind minions to leech XP/wait for regen.
It sort of makes a lot more sense in my head since I'm supposing I have a different playstyle from others, but it's just what I think
