Any of those three would do just fine soloing with casual play times. Pick the one you think sounds the most fun and you're good to go.
Druids are so damn versatile as a casual class, in your shoes I think I'd try one. Sow and ports let you avoid "wasted" time travelling to new areas or to groups if you want to join them. You can root and dot and nuke stuff early on, using charm to xp becomes an option at 14 and most people say it is the best xp possible for a druid, and then you can quad also some time after that. You aren't LOVED in groups, but you fit into them quite nicely anyways, especially 1-40.
Necros and enchanters are more capable of digging down into the depths of a dungeon and taking advantage of high zone experience modifiers, but and enchanters are very desired for groups.
But yeah, any of those 3 will work just fine for you, pick the one that sounds the most fun based on reading a bit about their strategy/spells on the wiki and start playing
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As far as starting locations, qeynos area has gnoll fang quest and diseased wolf/bear pelt quests that can get you some sweet xp and a fair amount of money as you level from 5-15 or so in qeynos hills and blackburrow. If you go druid you could then hit the karanas to do your charming if you wanted to. Gfay area has a lot of other players around if you want to do any grouping; before 20 especially you can find groups no matter what class you're playing. If you go necro you should (imo) be an iksar, which would mean field of bone ftw! Finally, if you start out in freeport/neriak area, EC is full of high levels who are usually happy to buff you to help you get through the early levels and maybe even help you out with some handmedown gear.