Comparison Between SPICE Simulators
My short answer is to just go with LTSpice, it is one of the best simulators on the market and it is free. You can't really beat that. But if you would like a breakdown feel free to read my personal opinions.

HSPICE:


Advantages: HSPICE is widely considered one of the most accurate simulators on the market. However I have no actual experience using it.
Disadvantages: As you said, it is expensive, proprietary, and as far as I know has no schematic capture features.
Overall: If you REQUIRE reliable results (Military or high end industrial) then HSPICE is the way to go. Otherwise, I would avoid it.


LTSpice:


Advantages: If you are doing power electronics this simulator is tuned for simulating switching events, as well as some other things which make it perfect for this field. Additionally, it has (IMO) an intuitive interface and doesn't try to hide the netlist from you. Plus, it is FREE.
Disadvantages: ? I haven't been made aware of any, it isn't considered quite as accurate as HSPICE, but it isn't inaccurate by any means.
Overall: This is the simulator I would suggest. It is easy to use, it is free, and it is supported by a much larger company. (Linear Technology)


ngspice:


Overall: I don't know enough about ngspice to give a full overview. I only recently downloaded it and am still working on compiling it for my system. Obviously you have found one of the drawbacks is being limited to the command line.


PSPICE:


Advantages: Well this is as close as you can get to the original SPICE. PSPICE is powerful, has a well established simulator, built in results viewer, and an extensive model library.
Disadvantages: Unfortunately it has become so bloated in recent years that it is difficult to recommend. And as you would probably like to have it on your computer, I would bet this one is out of your price range unless you have $20,000 laying around.
Overall: Powerful and well established, but going downhill fast. Expensive.