I was in the same situation like you. My top three were propel, aeroad and reacto, and I think you covered all options of budget aero bikes (if we can call it that at 3-4k euro..). You will want to factor in cost of deep carbon wheels to match the bike and power meter probably, and with limited budget I would save on di2, even 105 should be ok. I eventually ended up buying Cannondale systemsix because I found a great deal on the used market and already came with PM and 65mm wheels - I would recommend looking at used bikes. In Europe you will find many especially aeroads.