the most accurate answer for you is: "it all depends"
Seriously - what some people think is really fun - others cannot stand and are intensely bored with.
To get the best responses here - you'll need to give a little information on what you already like doing (what other games have you enjoyed where different character classes are an element? what fighting styles suit you? etc) but the best way is to just play the game and find what you like - maybe read through the skills descriptions for the classes and pick one that looks interesting.
it seems like you are just beginning, just start playing and try what looks best to you.
some basic points:
- there are several viable builds for every class
- almost every build can solo at least through nightmare
- for almost every build you will need at least half decent gear for hell
- plan your build, focus on the main skills, dont spread your skillpoints all over the place
- put only as much points in strength as you need to wear your gear; never points into nrg; dex only if your char want to go max block with a shield; rest into vitality (there are exceptions, but you will read about them in character guides)
- when you are gathering your equipment, think about the different sources you got (finding stuff, runewords, crafting, vendors and gambling)
once you have a slolid idea of what you want to play, you can either try yourself of course or look at the stickied guides in the class-specific forums. everything that works has already be done, so you will find information about it.