We all pick a XV before the 6N gets underway, made up of players from the 6 teams. No selection rules except that they must be available for this 6N (so no Mako, no Tuilagi, no Ntamack, etc), just pick you think is best. Then at the end of the tournament, revisit your selections and see if you'd make any changes.
I'll get us underway and upset our celtic cousins at the same time

Genge
George
Furlong
Itoje
Ryan
Ollivon
Curry
Aldritt
Dupont
Ford
May
Fickou
Ringrose
Watson
Hogg
Obviously it's not my 1st choice full team, I'd pick Mako and Tuilagi in there for sure, but that looks like a balanced and aggressive team to me.
No Welsh players doesn't mean I don't think any are good, it's just they're all in positions of strength (Tipuric up against that backrow, Jonny Williams against Fickou, 1/2p against Hogg...).