After my full-on spending binge (about 24M) I especially like the V-65 Motolok (Russian MIG-15) as the best of the pack. It's ace.
I also think the Western Rogue is great in a retro-collector sort of way, just not as powerful, but looks fantastic. I also like the LF-22 Starling, funnily enough, which looks a bit idiotic at first, but upgrades wonderfully and has an additional rocket boost. The Mammoth Tula is also pretty special, but the most expensive of the lot.
In a nutshell, all the military vehicles are welcome additions to the game and will look great in your hanger.
However, the non-military vehicles are a bit pants.
The Alpha-Z1 looks great on the Elitas website, but handles horribly, and looks crap in the awkward way it sits on the ground on its stunted wheels, like it's broken or something.
The Nagasaki Havok is pointless - a mini-helicopter to look like an inflated Bond villain in. You can call it as CEO vehicle, but so what? And the swaying machine gun? Pretty useless. Very expensive too, and disappointing.
The Unarmed Ultralight is pretty pointless too, but kind of charming though.
In terms of drip-feed future content - I'm really looking forward to the P-45 Nokota (P-51 Mustang, WWII fighter), and the FH-1 Hunter, obviously.