No need to fuss about picking which characters if you are just starting off. Just create a character for each class in HC and play with all of them. Get them all to the Skeleton King (SK) and then decide which one you are more comfortable playing. It will only take you max a couple of hours per character to get to SK and you will have a feel of things by then.

Also, playing multiple characters will net you more gold and/or gears for the character you ultimately decide to run with.

Plus the fact that in the unfortunate event where your chosen character dies, you will at least have the consolation that you have another character to fall back on.

Tips:

1. Always keep gears you want in your stash. If you keep them on your character's inventory, they will be gone if that character bites the dust. Death can happen when you least expect it.

2. Always keep a good set of lower level gears in your stash. If your main HC dies, at least your new character will have decent gears to start off with.