From what you said here, definitely Irelia.
Volibear's an alright top, he's one of my main jungles though and I feel that's definitely where he does best. Having to run through the enemy minions to get a Q off isn't really the best strategy for trading, and he lacks real escape mechanics since the MS boost on his Q is very meh when he isn't running at an enemy champion. Chances are that if someone's chasing you in lane and you're close enough to hit them with your slow, you probably won't be getting away anyways.
Fiora's all damage and no utility. She's unstoppable if fed, but if she falls behind she's practically useless. Bit too much of a gamble to try and carry in low elos as teamwork isn't really a very powerful driving force there. Most people are more worried about their own KDAs than making the right choices to get a victory screen.
Quinn is interesting, to say the least, and she has pretty safe laning phases because of her range and excellent poke. That being said, she isn't really a very hard carry, and since you end up building like an ADC with her she can be shut down in much the same way as one. Without the movement bonus on her ult her best escape mechanic is her targeted rebound, but that's only useful if the gap close to you. She might have a solid early game, but her late game isn't really the greatest as far as top laners, or even ADCs, go.
Irelia has a health amount of sustain, true damage, two different CC options, a targeted dash that resets on kills, and a ranged ult that applies her sustain. Her early game can be a bit shaky if you aren't careful, and she can have some mana issues if you're wasteful, but all in all she can survive well early game. She has a great midgame, and going into the late game can either be a highly damaging threat or an annoyingly unkillable offtank, and she has a LOT of different build paths based on what the enemy team is composed of. Several high health enemies? Build a BotRK. Squishies? Rush that Triforce. Falling behind? Start stacking tank now. Well ahead of the competition? AD through the roof and start blowing people up.
Out of the list you chosed, Irelia is the most solid top laner, and brings the most to the table. Even if I love Volibear to death.
She also has the frostbooty skin.
as it gives her a big powerspike and turn it into a 
asap. You can go all tank after that if you need to. That's how most people play her. If you need a second damage item 
or 
are good. If you are jungling with her you probably want to rush a devourer then rush a TF.