I'd advise a Necromancer/Monk. The monk mainly for resurect skills, if you run around with henchies you will need to resurrect them quite often
Necromancers are very powerful. In the beginning minions help with keeping the aggro of your back, since they'll be in the front meleeing. As long as you have bodies, you have minions, and if (one of) your henchies dies, you'll have even more minions

You can still resurrect the henchie after the fight.
I found that the problem with soloing (with hencies) quite often is getting mobbed, if you have several minions, you can even the numbers a bit.
Later on, you can change to blood magic if you want, which can deal a lot of damage in a very fast time. It stops you from getting bored of the same build, and it means that when you run into an area with enemy necros or monsters that don't leave a body (elementals, skeletons) you can still do a lot of damage. The healing wells are nice as well, and help keep your henchies alive.
Some Blood magic spels require oiu to sacrifice some of your own health, which I was not comfortable with at low levels, but at higher levels it seems to matter less. Make sure you have some health stealing or self healing skills to offset it though.
Both with minions and with bloodmagic you'll be clearing out areas pretty fast, in certain areas all I have to do is spawn my minions and then I sit back, watch them clear the area and pick up the loot after them

With bloodmagic I can sometimes kill enemies of the same or higher levels within seconds.
I am still new too GW (300 hours into the game now, 60 with my Ne/Mo) but this has been my experience so far. I am usually playing by myself because I can be on at strange times, but I do team up with guildies as well. I found these builds working in both cases, and most important:I'm having fun with this class combo.
