Rylais vs Rabadon on Vlad
Most pros seem to build Rylais on Vlad as the first major AP item. Very few people build Rabadon as first major AP item.
Should you though?
Rylais is a good item on Vlad, it has tons of synergy with the kit... it slows all enemies (giving Vlad a ton of instantaneous non-skill-shot perma slow), it allows him to kite targets and lock down targets for the team, it also has the bonus of going health on top of 100 AP which synergies with his E health scaling.
However, Rabadon gives you 120 AP + 1/3 of all of your max AP. That is a TON of damage. Usually, you already have a Zhonyas or a Hextech Belt built before (since you need max CDR as Vlad) and so getting this item gives you a lot more AP than going Rylais. It basically allows you to nuke your targets if you reach them.
I find that I prefer Rabadon. The game is usually decided either before or around the time you hit 3 major items in the build. Hence the choice of the first major AP item is huge. If you go Rylais first before getting Rabadon you're not dealing as much AP damage as you can in the time frame that really counts. I'm not sure you can afford it in such a fast meta. With Rabadon, you don't have perma-slow so it will be a bit harder to kite but the new Vlad is more like a dive champ anyways (someone who rushes in with Ghost and then stays in range of his attackers to deal damage while taking damage to maximise AOE output), kiting really isn't necessary.
Contrary to popular opinion, you also don't need Rylais to stay on top of a squishy target. If you take Stormraider's Surge, one E on the target gives you a movement speed boost which is usually enough for you to follow up for a kill. Your overall damage output is so much higher with a Rabadon than with Rylais.
What do you think though? Prioritise Rylais or Rabadon on Vlad?