As hammyhamster1 said, there’s no problem playing just the base game. Look in Build Compendium V for builds; everything I’ve tried has worked just fine. Or if you have an idea of what type of build you’d enjoy (melee/caster/ranged; what damage type; tanky or glass cannon; that kind of thing) I’m sure people would be happy to offer suggestions.
From my own experience, the smoothest, easiest to gear character I have is based on Superfluff’s Conjurer build, the most fun has been a 2-handed melee lightning Warder that I don’t seem to have based on any specific build, and my most capable character (so far) is based on Superfluff’s Commando build. Honorable mention to Weyu’s Trozan’s Spellbreaker build - not the most powerful thing ever since it’s a bit squishy, but I really like the playstyle of jumping in and dropping TSS on everything’s head. 
Don’t bother paying attention to the later Build Compendiums. With just the base game you can only reach level 85, so all those level 100 builds with Mythical items are irrelevant until/unless you pick up AoM. And even the devotion maps won’t make any sense since they added a fair number of new constellations in the expansions.
Some of the updates have also nerfed base game gear, which is why I haven’t updated from 1.0.7.1 (also, I’ve only played intermittently these past couple years, so laziness is also a factor). Losing the +1 to all skills from the Empowered Essence of Beronath and the +1 to all Nightblade skills from the Unseeing Eye of the Blind Assassin would severely impact two of my level 85 characters.