Welcome new member.  There are a number of Toyota experts on the forum, so you’ll probably get an answer shortly.  In the meantime, check the archives using the search bar above; this question (Toyota 4 vs 6) has come up before, and you should be able to find several opinions.

Cheers!

The V6 is obviously more powerful and will use more gas. A little less obvious is that it will be more expensive to service over its life. For example, I believe that like most modern V6 engines changing spark plugs involves removing the intake manifold. Of course these days spark plugs can last over 100K miles but it will need to be done at some point. (There may be other services that are higher cost as well.)

The 4-cylinder produces less power but is still pretty strong, uses less gas, and is easier and less expensive to service.

So, what's your pleasure, more power or lower operating cost?

do you want power or do you want fuel efficiency?

Test drive them and see.

I personally feel like the straight four is a little underpowered for the Highlander but if you like the drive it's definitely going to be cheaper than the V6  in up front costs and maintenance and gas

I personally prefer the inline 4 because it is slightly cheaper to maintain.  But if you need the power, get the V6.