mid veigar is one of the hardest characters to play against (imo). So, what do you think?
Galio is a good option but I don't like him.
People will hate me for violating meta, but Volibear is an incredible Veigar counter in mid. He's too tanky for Veigar to damage significantly in early level without wasting that farm q. Open with magic resist, and even that can't hurt you. Your q can keep up with him and set you up for nasty auto attack and bite damage. It's disgusting. Be agressive and exploit your early advantage, and you'll set him back for the whole game. Probably force their jungler to camp you, taking stress off your team, too. And Volibear is great at escaping ganks.
Few people will try that, though. Look at Teemo for his mobility, Lux for her cc, Gragas for his tankiness, and Ziggs for his range. (I've been harping on Ziggs being a good pro pick for so long. Just wait. Haha)