whicxh class is the best overall in your opinion.

Witches can be very powerful, but it'll take you longer to get to life nodes than other classes. This is important because a 5% increased life node is going to benefit you a lot more than a 10% increased energy shield node early on.

I recommend trying to get gear with spell and elemental damage if you're not killing monsters quickly. Scepters and Wands tend to be good for that. There are vendor recipes that can guarantee you beneficial mods, such as +1 to socketed lightning gems on your weapon.

On the other hand, if you're taking a lot of damage, I recommend trying to get more life and elemental resistances on your gear. You can't rely on the tree for life early on, so gear like coral rings, or leather belts can be really handy. Upgrading your items to magic or rare with life mods on them will also make a big difference to your survivability.

Good luck!