Sylas and Galio are super similar. Both are also overloaded at the moment. *Rant about specialists*
Sylas and Galio actually should fulfill a single niche, which is Anti-AP. Galio's W and his former identity led to the decision of a tanky form of this, and Sylas's ult stealing scales much better with AP, because his other abilities also do that, while the rest of his abilities suggest "lockdown assassin / diver".
Do not tell me that Sylas is an AP Bruiser. If he was meant to be an AP bruiser, then why would his Ult be such a specialist ult? Doing such a thing is only good for "MuH uNiQuENess AppEaL", and not healthy for gameplay. If he was meant to be an AP bruiser, make his ult something like Jax's ult, where if he activates hit, his passive's auto procs are increased in damage and he gains increased resistances, rather than this disgusting power shift. I understand that his ult is inconsistent, but Riot's balance team thinks it's OK to keep his damage high in other parts of his kit and make it seem like his Ult's power budget is low. It's really not, and when played against certain team comps, it renders them useless.
Here's the problem. Damage is way overtuned for both of them, removing the niche, and making them a generalist champion that oppresses a single type of itemization extremely hard while still being generally powerful compared to other all-around Assassins or Bruisers or whatever the heck Galio is now.
Galio is supposed to be a tank with cc, but now has a Q that does more damage than Assassins' abilities, while Sylas has a shield for at least half his health lategame, with a heal for just as much.
Right now, both of them have too much of everything. Galio has tankiness through aftershock, W's taunt, and his W passive shield, so hit some of his damage in return to give him the core idea of remaining an anti-mage tank, and Sylas is a mix between an assassin that does team wide damage with 3 dashes, a MASSIVE heal, a MASSIVE shield, a 9 second ult cd, and aoe slows. Nerf his damage AND his sustain. Either keep him as a "table flip" anti-mage that turns an AP mage's ult back onto them, by nerfing his generalized damage and sustain, or turn him into a fighter and add some sort of damage reduction on his ults.
Look at Sylas' Ratios:
http://leagueoflegends.wikia.com/wiki/Sylas/Abilities
Sylas's Q alone has 120% AP scaling, not including base damage. (I am not leaving out base damage to skew the argument. I'm just too lazy. You can see them for yourself, as they're quite high.)
Sylas's W is a targeted dash with 55% AP scaling, and a heal with 40% AP scaling that doubles.
Sylas's E is a 2 part dash with a 90% AP shield, stun, 0.5 second displacement, 20% AP damage.
His ult is self explanatory. Copy an ult, deal it back.
2nd part: All Hijacked ultimates and abilities that do not scale with ability power have their attack damage ratios converted to ability power ratios, scaling with 0.4% AP per 1% total AD, and 0.5% AP per 1% bonus AD. PYKE COUNTER ON AN AP COUNTER CHAMPION OK
I honestly don't know what the heck is going on with this last patch. As a Vayne main, wtf. Unneeded, and other marksman need nerfs, rather than buffs on "underpreforming" adcs. No significant damage nerfs, despite saying mutliple times that this is a "high damage meta that we're going to look at".
Specialist should honestly be a class, and I feel like certain champions would fulfill this niche well. Sylas and Galio are obvious choices, but also Urgot, because of his AOE Range and tankiness, Katarina the Janitor, and Twitch the stealth assassin ADC, and Aurelion Sol the ganker Mage. These champions (or reworks) were designed to have obvious weaknesses to compensate for their strengths. Katarina's is that repositioning away from her daggers can be VERY easy. Urgot's is that he has no real way to engage at range. He has to either land Q, or flash while dashing to truly engage a ranged unit. Aurelion Sol has a weakness towards many close range assassins. His Q recast buff does not mean that he'll be guaranteed survival, as his stars will still not hit unless he deactivates and speeds away, which reduces the damage. Also his health early was still kept to be puny. Twitch's early game is a meme, and is worse than Vayne's.
Sylas maintains ranged presence with a slow in an AOE fasion even at level 1. Galio doesn't sacrifice any of his damage, and instead uses his Anti-AP gimmicks as generalist tools, and builds like an assassin. Where are the weaknesses for either?
Meme:
I suppose Riot's way of making tanks relevant again is going to eventually be: "Tanks are the only class that can survive more than 1 second in a skirmish."
On another note, I played HOTS for a hot 2 days. Jaina is THE "burst mage", as in her literal role in the HOTS meta is "Bursts down targets with 1 spell rotation" but a full rotation of her spells deals maybe 3/4 health of an enemy squishy, and she has no mobility whatsoever. She does get a 20% slow on all her abilities though. She also has a fair amount of cc in one choice of her ults, that roots for 3 seconds, but it is hard to land without proper support.