QM is much better for xp, also if you plan on playing quite a bit buying a stimpack is worth it. 100% xp and 150% gold bonus is nice.
75g for a win and 50g for a loss ain't bad.
Rehgar is really good and that instant full heal ult can win a fight for your team. That said I don't like playing him either.
Nova is very hit and miss, good Nova players are a pain, bad Nova players are easy picking.
My favs are:
Muradin - Love the stun and the passive healing is great. Plus he has the best master skin.
Zeratul - Stealth, blink and a decent amount of damage.
Sylvanas - I love lane pushing as she's a beast and disabling structures is great.
Jaina - Best burst damage in the game along with Nova. Squishy so positioning is everything.