Some overview of melee builds for you:
Barb: many different variations, strongest char since MXL:2017 release, really flexible, covers all ubers and has very good farming builds. Gets nerfed in 1.3, but most likely still going to be very solid melee char still.
Paladin: Holy melee is really strong option, tanky, mobile, has decent damage. Suits well for getting charms, but can be nice farmer if built properly aswell. Unholy melee, as already said, is rather weak, especially if compared to meta melee builds. Constant unholy tree nerfs hit him quite hard, so I wouldn't recommend him for new players.
Druid: Treewarden is amazing. Insane damage, acceptable tankiness, good sustain. Has some issues with certain bosses (astro, for example), but he is able to complete 95% of charms with really basic RWs and crafts. With proper gear setup can be used as a farmer aswell. Werewolf is pure farming build, not sure how avoid swap in this patch is going to affect him, but he used to be one of the fastest farmers till this patch. He is absurdly bad for getting charms though.
Amazon: Pouncezon is rather crappy build in general, suits for farming certain ubers. Honestly, it's not even worth to count her as a individual build, just value her as "I have a zon and I want to farm some dunc".
Necromancer: Melee nec gets reworked in 1.3, single target skill gets buffed, famine passive reworked. Pre 1.3, scytche used to be pure farming build, due to the lack of sober single target damage, maybe situation will change this patch. Dagger nec has lower parasite damage, but has access to the ancient hand oskill, so it was even possible to get some charms with this guy. AH nec is considered as a exotic build, due to it's questionable practicability and restriction to the crafted weapon (if you want to play like a human, get charms with totem and farm with scytche parasite).
Sorceress: Didn't touch melee sorc for many years, so cannot surely say. Bladestorm targeting is total cancer, but not that long ago she got some new skills in her skilltree and considering in what epic state caster sorc builds are now, it doesn't sound like the worst idea to give her a try, if you want to play sorc that badly.
Assassin: Melee sin sucks. Only more or less viable build is noctule, and even it gets outshined hard in terms of damage and tankiness. Melee assassin is good for farming end game charms (max block, avoid, flat dr/mdr from passive, qob is op vs purify bosses) with full sigs, charms and gg gear, but gl getting there w/o trading and twinking.