The only components that are 'weight sensitive' (ie more likely to be adversely affected by a heavy rider) are the wheelset, and maybe the seatpost.
A derailleur or shifter doesn't care how much you weigh. And anything above the bottom level of cranks, frames, chains, etc. are, in my experience, more than adequate for a few seasons under even very large riders.
As for the wheelset and seatpost, select the bike that fits you (comfort-wise), then have the wheels and seatpost upgraded (32 or more spokes laced to Shimano hubs, and a Thompson SP respectively) before you take delivery.
As for the rest of the components, what happens if they wear out or fail? Replace them with more robust components when the time comes.
The most important feature of a new bike is the fit. Everything else can be fixed as time goes on.
So to more directly answer your question, I would suggest Tiagra level components as a minimum as I think they represent good value and reasonably long lasting parts. 105 parts will last longer, and Ultegra will last a little longer than that. When new there is very little difference between the performance of the groups.