Personally, I would avoid Abacus at all costs if you are looking for high quality stuff. From what I have seen they make the worst payware out there. I'd rather spend my $30 on one high quality aircraft, rather than a box full of really crappy aircraft, which is basically what you get, but since I've never actually owned any of their stuff my opinion might not be worth anything.
Unfortunatly there's not much out there if you are looking for shootable weapons, though you can get some nice military aircraft. The best modern fighter out there is the F/A-18 with the acceleration pack, and if you have that you can get the Captain Sim XLoad which has full weapon loadouts that have accurate weight and drag affects on the flight model, though they are not shootable. The Captain Sim C-130 is the best military transport plane out there if you are into those. Awesome flight model and a very fun plane to fly.
Iris Simulations has a new F-20 Tigershark thats worth a look, and Alphasim has a ton a military offerings, though you won't get the level of quality from either company that you see with the F/A-18. I do really like the Alphasim F-86 saber as its got a very nice external model and flight model, but with all Alphasim stuff the VC is not the best. I'm familiar with a few of the Iris and Alphasim offerings, so if you are looking at anything specific and can let you know what I think.
If you are looking for Warbirds the RealAir Spitfire is clearly the best choice, and nearly everybody who posts here has it, and I am also a big fan of the Shockwave(A2A) P-40, which is a close second behind the Spit.
Most of the planes I fly are military, and I've created a visual catalogue of my recommended add ons in this