If you try out a few Lamys you realise that fountain pens work according to the flat earth turntable philosophy; the deck is more important than the cart, and the pen body is more important than the nib.
I found that after numerous other fountain pens, a Lamy CP1 has the perfect weight and sleek minimal style. I stopped spending much money on pens because I always lose them, so this Lamy is perfect. I think in visual design, it is what you asked for; the Rega RP3 of pens, and the Lamy nib, on a good body, is surprisingly decent. I find it smoother than the other options from Waterman, Parker, Schaeffer, Cross etc for under £70 or so.
Ultimately you need to decide whether you prioritise smooth action, speed, precision etc, so you need to try them out.