Utility
The ES 350's larger trunk will accommodate more large items than the BMW 3 Series.
Neither the BMW 3 Series nor the Lexus ES 350 has a marked advantage as far as seating capacity.
Dimensions
The Lexus ES 350 is a tad heavier than the 3 Series.
Your wallet will hurt more every time you fill up the Lexus ES 350 than the 3 Series because of its more capacious tank.
The BMW 3 Series and the Lexus ES 350 compete for the same parking spaces.
Convenience
You'll very likely have to take the BMW 3 Series for a fill-up more often than the ES 350 because of its tank size and fuel economy.
Cost
In terms of fuel economy, the ES 350 and the BMW 3 Series don't differ much.
With respect to MSRP, the BMW 3 Series costs about as much as the Lexus ES 350 (though the Lexus ES 350 is a bit cheaper).
Regarding final cost, the Lexus ES 350 doesn't cost much less than the BMW 3 Series.
Handling
The 3 Series's rear-wheel drive layout likely gives it better dry traction than the Lexus ES 350; on the other hand, the Lexus ES 350's front-wheel drive layout likely provides better traction in rain, snow or ice.
The BMW 3 Series and the Lexus ES 350 have about similar tires.
With their comparable turning circles, the BMW and the Lexus ES 350 quite certainly handle approximately the same into and out of tight spots.
Drivetrain
The BMW 3 Series's engine is considerably smaller than the ES 350's. Remember that smaller engines can be stressed more; however, smaller engines are often cheaper to fix.
Torque equals pickup, and the Lexus ES 350 will have picked up and gone by the time the BMW 3 Series finally gets moving.
The BMW 3 Series could learn a lesson or two from the Lexus ES 350 regarding pickup.
Comfort
The Lexus ES 350 is not particularly more spacious for your passengers than the BMW 3 Series.
Overview
The Lexus ES 350 and the BMW 3 Series have the same basic warranty.