So, It's been a few years since I've played and I don't know what class to pick. I know Mercs are useful but like.. I want to play a class that can solo without a merc easily, I do like being able to heal myself as well as others, but I also prefer good DPS and I tend to like AoE spells/skills. I don't mind not being able to heal though, it's fine.
If you like melee, then shadowknight fits your criteria for soloing (my SK is DPS-specced). If you want to group, though, then the SK is expected to be a tank. Has lots of AoE damage spells. For the healers, fury has the most DPS, good self- and group-heals, and AoE spells.
For mages, necro would be high DPS with good soloing capabilities (one of the best soloers in the game without a merc). Very capable at self heals, not so much on healing others (other than their pet). For scout, I play a ranger, so have to admit a strong bias, but ranger is a very good soloer as well, but little to no healing component. A well geared and played ranger has little need for heals though, nothing beats watching them fall dead at your feet. My ranger was one/two-shotting PoP mobs at barely 100 in nothing but the chest gear, no adornments. I run Bhoogar for convenience with cures and heals, really can speed things up, but not required. Swash is a much stronger AOE scout, but positional requirements makes it much more difficult solo class, esp. without a merc. Never played one, but have heard good things about berserker. These days, esp if you do use a merc, about any class solos well. They have really made it much easier on solo players over the years. Things get more complicated when you raid, and gear/AA/rotation becomes far more critical. But for strictly soloing, choose the class that appeals to you for play style, and go for it!
My opinion, as I have and have played one of every class: Fighter = Monk, SK or Pally. Monk gives you the ability to feign death and some heals, which is the best in fights. SK > Pally, but these two have marked differences in abilities that some people prefer the pally. SK is also OP. Scout = Brigand. It's a tank in chain. I prefer playing the ranger, but I live a lot longer on a brigand. Mage = Necro. Necro has self-heal spells, a tank pet that can really tank, and a few other good things. Of course, I don't like playing a necro, I prefer Illy and Conjy. Healer = Fury. Fury has the best DPS of the healers, so you won't feel like you're taking forever to kill a mob. Wardens and Inquisitors also can do good dps, but at a slightly slower rate. This is specifically in answer to the question you asked, about soloing without a merc. Personally, and the same is true for a lot of people, I would try out all the classes again to about level 25-30 and see which one you like to play the best in the here and now. Just because some classes are more powerful, doesn't make them more fun. I would also take the Queens Colony/Isle of Refuge start zone first, because it's a bit tougher than FFS/DLW/TD. You will know before you leave the island how easy/tough some classes are to play.
"Just because some classes are more powerful, doesn't make them more fun." Completely agree. I have a high level necro I hardly play because it's just too easy, and I get bored with it rather quickly.
Not quite so familiar with these archetypes, plus was working with your requirement for self-heals. As both Carynn and Faelan said, necro best for soloing and self-healing. I personally like my wizard better because I don't really like pet classes, and I like to blow things up. She's very squishy though (a glass cannon), and definitely needs to run with an inquisitor or tank merc to keep aggro off her. No self-heals (but does have a cure arcane ability). Warlock has good AoEs and spells to affect all members of an encounter in linked groups (wizard = single-target destruction using elemental damage; warlock = multi-target destruction using poison and disease damage). I have a couple of rangers that are good fun and do good DPS, but same as mages - inclined to be squishy in melee type situations. Rangers survive best when the mob can't touch them (kiting is my friend!). No self-heals though.
