TN F is basically C+ - six of the same seats they use in C, but they extend to fully flat, in a 2 x 2 x 2 configuration in a tiny, cramped cabin (they are 2 x 2 x 2 in C as well).
TN Poerava Business is quite OK, and a straight shot into CDG from LAX. Nothing against it at all, and I've enjoyed by TN flights; perhaps slightly more attentive service than IB. TN also means the Tom Bradley terminal at LAX - ugh!
IB Business Plus is a fully flat seat and a generation ahead of Air Tahiti Nui, better food and wine IMO, and the OP would get to use the excellent Velázquez lounge on the return as well.
TN has the flight to Paris, IB and AA have a JB and many more flights between Madrid and Paris.
In the end, depends on what is available - but IB offers greater flexibility, better hard product.
And, there's nothing to prevent the OP, if he wants some interesting experience (especially if he returns and shares with us!
) using TN outbound and IB return, etc.