which AD carries are the best/ in the highest tier?

Depends on the situation. Graves has high damage and has super burst capability. Vayne has the highest potential for late game. I don't like Corki much, personally, but I've seen him used extremely successfully lately in pro play.

Usually seen in the pro games are Ezreal, Graves, Ashe, Corki, Sivir, Kog' Maw. Urgot too but he is technically a "melee caster"

Not as much seen Vayne, Varus, Draven, MF, Tristana, and Caitlyn.

This is mainly just from what i've seen, they all have their advantages/disadvantages and obviously certain AD carries counter others. Some tend to be better at lower elos just because of the playstyle that is different from the "higher tiers"

I wouldn't really discriminate too much against the other ones tho. I personally hate playing Draven, Varus, and Kog' Maw meanwhile you may excel at them.

I didn't look up your account or anything so I'm kind of just assuming you don't know much about ADC. Anyways...hope I helped.

I use these as my main AD Carries. (I main adc)

I like vayne (a lot her harass and burst is amazing but she is tough to play with because she has no aoe's so it can be more difficult to get a lot of cs unlike a champ like graves who can use smoke screen/buck shot to farm cs.)

Corki (Great escape and his dps early/mid/late is amazing, I love the true damage!)

Tristana (really fun to play and takes skill to do well with.)

I would really like to play kog'maw but I can't afford just yet.

I don't like caitlyn at all she is soo squishy and her ult is useless against a good team. I don't like graves, he is over played and easy to counter. Sivir is decent in a 1v1 but her [Q] does no damage if its going through multiple targets and it just eats mana, although Sivir is amazing if they have a volibear or an varus on the other team because spell sheild is used often and regains her mana.

Never play ashe, she is by far the worst AD Carry of all time and is useless late game, way to squishy and is just over all a bad pick. There is a saying "you get what you pay for" and with ashe, that is true.

Graves and Corki are over used in pro games. Vayne is also very popular, as a harder carry with more risk and reward.

you of course see the rest on occasion, but i wouldn't consider them on the same level as graves or corki.

I wouldn't say Ashe is useless and the worst AD Champ at all. You usually have to play passively in the laning phase but if a jungler comes you can easily secure a kill with ult and perma slow.

Mid/Late game Ashe's ult is arguably the best initiator in the game and her W is quite decent range poke and good for quickly clearing waves. Although she has no real steroid or escape the CC she brings to the table can not be ignored.

This has been discussed before. I would prob go with graves though, cause he has more cc and aoe.

Graves = King AD. Good early, mid and late.
Kog = Built in Madreds, good range, gonna kill everything after IE/PD.
Trist = Probably best late game carry. Insane rage, knockback and jump to survive teamfights.
Vayne = One of the best late game. Has insane sterioid, shes gonna kill everything whether they have armor or not.
Urgot = Hella gay in lane.
Corki = Passive is insane. Has incredible burst in lane like graves, very strong late game.
Ezreal = Strong early game. Bad late game (compared to other AD)

graves/corki/ezreal > everything else

For me, It's got to be Draaaven or Ez because they are strong early