What you're really looking for is "satisfaction of ownership". Ride the bikes. Whichever one "sings" to you - don't over analyse why, just buy it.

Minor comfort differences are most likely due to finite differences in the saddle or handlebar position. Better shifting crispness is more likely to be due to fine tuning of cable tension than a 1 or 2 group component upgrade.

If the most expensive bike is the one that appeals to you, buy it anyway. A year from now you won't be able to remember how you spent the $300 that you saved but you'll still have the bike. If, everytime that you look at it you think "I wish I'd have bought the other one", it's not a good deal.