Thanks for the input, drck1000. If I decide to buy a basic first gun, would a Colt 6940 fit the bill, at least until I figure out what I really want?
PWS makes very nice rifles and while I have no regrets regarding my PWS purchase, they are expensive. And so are optics for it (which isn't unique to PWS, but slapping a cheap optic on an expensive rifle just feels like a disservice, at least to me). There are deals to be had online for the MK114/MK116, but at least with regards to the MK116 Mod 1, PWS appears to have had an earlier release with a shorter rail, then later updated them with a longer rail, so be sure to confirm that you are not being sent old stock.
That said, I agree with drck1000 that a basic AR would be a great starter rifle, so if you can afford it, buy both!

If you're set on purchasing a Colt, then I would personally choose a 6920 (assembled or in OEM configuration, depending on your needs) over a 6940. Either of them would suit you fine, however, if it's within your budget and will leave you with enough leftover for mags and ammo.