A nightmare? Lock On? You must be playing a different Sim mate, Lock on can be set to be as easy or difficult as you like, there are dozens of options for realism/arcade modes. There are tons of Sims on the way too as Dano pointed out.
To the OP download the Lock on demo and make up your own mind - Near the bottom of the page...
http://lockon.co.uk/index.php?end_pos=135&scr=products&lang=en ) A very good user made vid from lock on -
Other Sims to check out are IL2 1946 for WW2 air combat, Falcon 4 too is excellent, but it's a bit on the heavy side in terms of complexity. There is also DCS:- Black shark for Helicopter combat. For Vietnam era combat Strike Fighters 2 would be worth a look. Edit:- I forgot for WW1 flying Rise of Flight is on its way too.
A good site to start with is
www.simhq.com lots of info there.
Nate