F7 Ultra or IQOO 13? Which would be a better buy?

I assume you purchased the iqoo13 256gb version at 2.5k right?

One is this years flagship chipset another is last years flagship. 8 gen 3 is still powerful but your iqoo13 is even powerful which extends its future proofing.

Iqoo13 also has slightly larger screen with higher resolution display and a higher peak brightness with 144hz for a smoother experience with LTPO.

Camera wise iqoo13 is even better.

Software wise I think Funtouch has better software and security updates and less bugs and quirks compared to hyperOS.

Your iqoo13 has 6150mAh battery capacity. Battery consumption couldn't give a definite answer but judging by the reviews should be even better than poco.

Given the extra RM800 you paid I think it's worth it. So no need to be hard on yourself.