Roulette prices itself in the open. The European wheel has 37 pockets, numbered 1 to 36 plus a single zero. A straight-up bet on one number wins once in 37 spins on average and pays 35 to 1. A fair payout would be 36 to 1. That missing unit is the house edge, and it works out at 2.7% of every unit staked.
The American wheel adds a double zero, so there are 38 pockets. The payout is unchanged at 35 to 1, which means the same bet now wins once in 38 and the gap between fair and actual payout doubles. The edge becomes 5.26%. Two wheels, the same felt, the same chips, and one costs roughly twice as much per spin as the other. If both are in the lobby, the choice is settled.
On the European wheel the edge is the same 2.7% for every standard bet. Red or black, a corner, a split, a column, a straight-up number, all of them carry it. Spreading chips across the table does not dilute it, because you are simply paying the same 2.7% on a larger total stake. Covering more numbers narrows the range of outcomes, and that is all it does.
One rule genuinely helps, where the site offers it. Under la partage, half your even-money stake is returned when the ball lands in zero; under en prison, it is held for the next spin. Either rule halves the house edge on even-money bets specifically, and it is the only change on this list that alters the price rather than the feel. French roulette tables are where you will find it, so check the rules tab before assuming a single-zero wheel is the cheapest one available.