A couple of considerations.
While Oyster works out your daily cap, contactless also works out your weekly cap. You'd be charged the lower of the sum of your daily cap or weekly cap. Weekly cap is based on your ride from Monday to Sunday.
A weekly cap is roughly the cost of 5 daily cap totals.
Contactless covers a wider part of London and Southeast networks. For example, if you have to visit Windsor station of great western line, you can pay with contactless rather than oyster.
Same for Luton Airport Parkway and St Albans.
However, you can't enjoy railcard discounts on Contactless, but discounts of some rail cards can be loaded to Oyster.
Oyster card is not reused or maybe even recycled. Not getting a new Oyster card can reduce plastic waste.
There is no difference in user experience at all - in terms of tapping in and out.