[Semis]

Yes, Mazzy's a killer at long range. With the Tuigan Bow, she gets 5 (!!) shots per round, and a thac0 usually well into the negative numbers. Add improved haste to that... and I hope you stocked up on arrows! She can empty her quiver in 4 rounds! I have her in my party; she's great for disrupting (or outright killing) enemy casters. Up close she doesn't shine so brightly, but is still passable in a melee if given a good short sword. Her pseudo-paladin spells are also very helpful.

Valygar is pretty well the other side of the coin. Specialized in Katana and Dual-Wield, he can tear anything up that gets too close. But if you've had him before, I don't have to describe the sorts of carnage he can create with his family blade and, say, the Celestial Fury.
Plus, he can backstab... ouch!

So, who to choose? Well, depends on what you need in your party. If you have a dwarf berzerker, then you probably have melee all sewn up. Of course... you can always get both (unless the other four party members are indispensible).