Horses for courses and each to their own.
It all depends if the 7ES pros and cons suits your personal needs, wants and tastes.

7ES has certain up sides, and certain down sides.

The upsides include:
Exterior and interior styling.
An aluminium bonnet, front quarter panels and trunk lid - or does Camry/Avalon have this already?
Front strut brace, and rear V-brace to increase rigidity and bending stiffness - or does Camry/Avalon have this already?
Sports bucket seats front and rear.
Does Avalon have noise cancelling alloy wheels too?
Probably more sound insulation.
A thumping 1,800 Watt Mark Levinson Class D amplifier that does not have to work very hard, hence very little distortion to sound quality.

The downsides include:
Maybe 7ES has a slightly smaller cabin???
Maybe 7ES has a slightly smaller trunk than Avalon???
Due to rear V-brace, 7ES does not have rear folding seats.
7ES's bucket seats are great for 4 occupants, but Avalon's flatter seats with less lateral support will be better for 5 occupants!
Maybe 7ES has a firmer ride than Avalon???
7ES costs $10k more.

There are many many other differences between 7ES and Avalon...

Traditionally, the Lexus ES or Toyota Windom as it was called before the Lexus division was established in Japan in 2005, the ES/Windom was a sporty stylish hardtop/frameless window lower roofline smaller cabin/trunk with non-folding rear seat backrests, heavy duty suspension, quieter and better equipped version of the Toyota Camry, but I'm not sure if that is still the case today.

 

The ES will get jealous stares. The Avalon will make tasty waffles (with that huge grille).
So, what's more important? Envy or waffles?

 

Waffles go well with that brown interior. Sugar free syrup please.

 

This is a good point. I had always assumed that the Lexus ES was an upscale version of the Camry (not in a bad way) and thought that the Avalon was for those wanting a bigger car (than the Camry) but were not going to spend the money buying a full size luxury car like the LS, S Class, 7 Series. Now, it seems like Lexus is moving the ES to be same size as the Avalon which is a downer for me because it's feels bloated compared to the European brands.

 

Been on the Avalon platform since 2013. I think bigger is better and it does not feel bloated at all.

 

I sat in both cars the ES and the Avalon and compared them both, personally I like the ES350. I just felt the quality of the ES was slightly better, what really turned me off on the avalon was the flimsy (Felt like something that belonged in corolla) glove box, and the front bumper grille. I think they cheaped out! Hell, I liked the camry sport more then the avalon. My personal taste! I would def spend that extra bit of cash for a ES.