Kernow (and friend's) first ever bike build

Hi all -
after seeking parts to build my first bike (and own my first carbon framed bike) I've nearly purchased enough to build two bikes - rather easy to get carried away. The plan is to build two bikes and either
a) a bike each for myself and Curly - the brains, and tools , and garage, behind the operation
b) keep both as a winter and summer bike

More bits are in transit though I currently have a Planet-X nanolight frame, Tiagra 4700 full groupset and Fulcrum s-four wheelset plus extras enough to start building. The Ultegra BB I had in the shed fits like...well....fits like a BB that fits!
Carbon frame is sound bar a slight grumbling (no play) which means first job (tomorrow) is strip bearings, dismantle race and re-grease. Pics to follow tomorrow

First question - as I theoretically get first dibs on everything which groupo should I choose?

1. Tiagra 4700 (the new one) full groupo - well used but clean and in good mechanical order
   
2. Ultegra 6600 group with Dura-Ace 7800 rd - obviously older but also in good v
   nick and working order.
   Is it a no-brainer?
   
   

Thanks all and look forward to getting going tomorrow.

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