Looking for an experience similar to my Monk adventures.

[Vexenu]

Necro would be a good choice if you're looking for that sort of solo-adventuring, me-against-the-world vibe. Also a very thematic class. If you don't want another Iksar and enjoy faction challenges then go DE, their faction is similarly bad outside of Neriak/Grobb/Oggok. Downside of a Necro is you might actually find it not challenging enough to be interesting, as you can easily solo a Necro to 60 with minimal gear.

If you're wiling to impose restrictions on yourself, you can make things a lot more challenging for yourself (i.e. solo self-found) with any race/class combo, but particularly melees. Not sure if that's what you're looking for, but always an option. If you wanted to do another Monk playthrough you could go Human and work through the Sash/Headband and Treant Fists questlines. There's a lot of meat and thematic richness there, and they even tie into the Monk Epic.