Best solo class overall for heroic champ? Starting from scratch.

In my opinion, the single best skill for exploring old content is feign death. Being able to bypass large chunks of mobs, and just go to the mob you're interested in is just amazingly handy. That leaves you with monk, necro, or SK. Monk doesn't have a reliable snare, otherwise it would be top of the list to me. Between SK and Necro it really depends on what playstyle you prefer. An SK with a healer merc is immortal in lower level content, regardless of the situation. You also don't get into the problem of magic immune mobs (which there are actually a good number of in older content), that can really slow a necro down.

It's nice to have a character that can take a bit of a beating if you are going to explore/farm old content. You can just destroy stuff AOE with an SK and a healer merc.

So much of this depends on what you actually want to do. If you just want to tool around and see old content, nothing beats a bard. They are also incredibly fun. They don't kill stuff very quickly, but if your main goal is sightseeing, it's impossible to beat a bard. If you are going to be trying to farm things in bulk for other characters, something like mage is awesome because you can really burn through mobs quickly.

/shrug. The combination of bullet proof, feign death, snare, decent DPS and AOE makes SKs surprisingly fun and effective lower level content explorers. A bit off the beaten path, but they have some great utility for adventuring.

Sk are fine until mob hp increases in the 70's and 80's. Tank dps is so poor that it takes an eternity to kill anything. For 2 or more it's fine, but for pure solo I'd take Nec or monk over sk any day of the week.

If I was making this decision, I would go with Necro for most of the reasons already stated. Necros also seem to have some of the best top level DPS in the end game. My guilds top DPS classes are necros, hitting 130k dps at the high end. Mages are solid too, but overall with the way that swarm pets currently work I think Necros are a little stronger. Add in Feign Death and it puts necros over the top. Necros can solo places, due to FD and being able to pull better, that Mages have a hard time with.

The next choice I would go with would be druid. They have ports, invis, tracking, nukes, heals, snare.... it's a very versatile class. You can molo with a tank and you healing, you can root and nuke with a wiz dps merc, or you can just kite with snare.

Mages swarm pets are better than necros. I'm guessing necros are getting that kind of DPS by using spellsets to swap out their spellbars to load up 10+ DoTs on a raid mob. Which isn't all that practical or needed in grouping environment. My mage can out-dps my necro in groups

If you want to explore , Druid +T 5 Tank merc will let you do
a whole lot of stuff the others can't do.

Doozy
105 Rogue
105 Mage
96 Warrior
87 Monk
88 Druid
85 Necro
79 Paladin
86 Enchanter
100 Shaman