I would like to say, as of now, Vladimir is my strongest, and safest pick (being that I don't make too many mistakes). He has such a great late-game, and he can easily erase carries with his passive. He can reach ~700 AP when he is full build, and he is still tanky enough to cap a few objectives on his own. I have encountered some champions that have given me trouble in the past, but Vladimir puts an end to all of those lost lanes.

When you get into lane, your best skill is your Q - Blood Transfusion. It doesn't cost any health, it deals a large amount of flat damage at max rank, and also heals you. Max this first. You should take your E - Tides of Blood second. This will help you kill multiple minions at once, and each use of it, hitting something or not, will add a stack. These stacks add on to the damage of the next use, and stop at 4 stacks. Max this second, as it will be your secondary source of multi-target damage, and make you a crazy duelist. With your third point, grab your
W - Sanguine Pool. This will make you a pain in the *** to fight, and it also makes you very hard to gank (most times). It also deals a good amount of AoE damage, but costs a good deal of health. This health can be regained by moving under minions, neutral monsters and enemy champions, making up for the cost. Max this last. Your R - Hemoplague, is a devastating skill. It works much like Zed's ultimate, but it is multi-target damage. Casting Hemoplague will add a debuff to any enemy unit hit by this skill. The debuff increases the damage you and your allies deal to that champion, helping in team fights and boosting other AoE skill damage. After a few seconds, all enemy units affected will take a flat amount of magic damage.

I use 21-6-3 masteries. Now some of you may disagree with me on this, so hear me out, as I will have explanations for each tree.
OFFENSIVE TREE:
Fury :: 1/4 :: This extra attack speed will help you in farming.
Sorcery :: 4/4 :: Vladimir needs cooldown reduction.
Butcher :: 1/1 :: Vladimir will get some extra damage on minions and monsters to help him farm.

Expose Weakness :: 1/1 :: Increases ally ganking damage when you use skills on a target.
Feast :: 1/1 :: You will be healed when killing units.

Spell Weaving :: 1/1 :: Auto-attacking an enemy champion will boost your skill damage.
Executioner :: 3/3 :: Need I explain why?

Archamge :: 3/3 :: That extra 5% ability power will go a long way late game.
Dangerous Game :: 1/1 :: You will regain 5% of your missing health when killing an enemy.

Devastating Strikes :: 3/3 :: That extra magic pen will shred through your enemies.
Arcane Blade :: 1/1 :: This will boost your atuo-attack damage, making farming easier.

Havoc :: 1/1 :: Increase % damage will help in your road to dominating the enemy team.


DEFENSIVE TREE:
Block :: 2/2 :: Blocks small amounts of damage that may have ended up killing you.
Enchanted Armor :: 2/2 :: This will give you a lot of sustain in the early-mid game.

Unyielding :: 1/1 :: Again, this will help with sustain.
Veteran's Scars :: 1/3 :: That +12 health will help you in the early game.


UTILITY TREE:
Phasewalker :: 1/1 :: That one second can give you more map presence, so you can roam.
Fleet of Foot :: 2/3 :: This will allow you to catch up to enemies to potentially get more kills.

I go with the every-day, regular rune page with only one change. All Runes Are Tier 3.

Mark of Magic Penetration x 9
Seal of Armor x 9
Glyph of Magic Resist x 9
Qunitessence of Ability Power x 2
Quintessence of Experience x 1

**The qunit of experience will help you level up faster than your opponent, potentially chasing them out, and killing them more often, and putting them on tilt.**

For me, Flash and Teleport work well. I have a lot of map presence, and I can also safely escape from ganks if my pool isn't enough. But Flash/Ignite, Flash/Ghost, and anything else that works for you and you're most comfortable with is just fine.

Pros of going AP Carry Vlad:
-You will burst people down, allowing you to essentially snowball the whole game.
-You will be a great asset to your team.
-A great deal of your ability power will become health because of your health.
-You will be a crazy duelist and split pusher.
-There are many items for you to start tanking with without losing a majority of your damage.

Cons of going AP Carry Vlad:
-You can get shut down early game by some of the other top laners of the season.
-You can lose your lane easily if you don't play right.
-You may be focused if you start to do too well.

When you're team fighting, a good strategy is to ult as many enemy champs as possible (hopefully they all group up, or are in a tight place, like the jungle), and allow your team to wombo combo them while you pool under the enemy team, dealing damage and also slowing them. This may win you every team fight if done properly.

Your Expose Weakness mastery will help your jungler deal more damage, resulting in a successful gank, and possibly a won lane/game.

Your Sanguine Pool can help allies to escape. The slow and damage will cause the enemy to either take unnecessary damage, or run away.

Vladimir is good against almost every champion in the game, with the exception of Fiddlesticks, but that's only his W.

Vladimir is amazing against:
-Any melee champion
-Any champion with skill shots that can be blocked by minions
-Any squishy champions with no good escapes
-Any mana hungry champions
-Any champion that has a targeting skill

Vladimir is not so great against:
-Any lock on skills like Fiddle's W
-Heavy CC champions
-Champions that have ridiculous immunity skills like Fizz
-Silences like Garen's Q
-Ignites
-Teemo

Some specific match ups are:
Lee Sin :: Stay behind minions, farm, and if he gets in range, Q him, if he stays too close, E, and Q again. Some Will try to jump to a ward, just pool and initiate a combo on them so they have no time to react and they are put into a bad situation. Re-position yourself as needed.

Sion (4.18) :: Keep using your Q. His knock-up is so easy to dodge, and leaves him open to a lot of damage. If he ults, W under it, so hopefully he will go under your turret. Pool under his passive, it is very strong for no reason, and he can make any trade into a one for one.
Demolish him when he misses his knock-up, use your ult and begin to unleash your thresh hold of doom onto him.

Darius :: Your Q out ranges all of his skills, but only by a tiny bit. Make sure you run away right after you land your attack. After he misses a pull or a whole combo, unleash all hell upon him. You can W under his ult to completely avoid it. Don't get pulled by him. He will literally kill you within seconds if he is above 6.

Rumble :: Same deal with Lee Sin. His harpoon does little damage, but has a massive slow if he hits both times. His fire deals little to no damage, and if he is that close to you, you can unleash your whole kit onto him. His ult will wreck you, and it's not worth a pool to get out of it. Immediately start using your Q or some pots to heal back up.

These are the only champions I have fought so far in the top lane. Other champions are very easy to read and counter, and remember: YOU ARE THE BULLY.

Don't laugh, but the recommended build is actually the best way for Vladimir. It has the perfect amount of health, armor, magic resist, and ability power to completely trash the enemy team.

If you need to change items in your build to counter other enemies, do so.

Starting Items:
Boots
Health Pots x 4
Warding Totem** WARD!!!!!

First Back:
Boots of Lucidty with any echantment :: Furor works well, but I prefer Homeguard.
Wards** I cannot stress this enough. Ward all the time. You will die a LOT less if you do.
Will of the Ancients

Core:
Spirit Visage
Rylai's Crystal Scepter
Zhonya's Hourglass
Rabbdon's Deathcap

Vladimir is a very strong champion overall, and in the right hands can carry every game.
Here is a link to a few matches I've recently played, just to show you that this DOES work.

Full Build
http://matchhistory.na.leagueoflegends.com/en/#match-details/NA1/1584874815/205669631?tab=builds

Almost Full Build
http://matchhistory.na.leagueoflegends.com/en/#match-details/NA1/1584873620/205669631?tab=builds