I would recommend holding a few months off. Nokia 8.1 launch is around the corner, and looking at the China variant, the selfie cameras are at par with the f9 pro
For Oppo F9 Pro, @Dinesh jain bro may help you as he recently purchased it.
I'll suggest you to wait for few weeks as Realme is going to launch Realme3/pro which will have Helio P70 & obviously there camera will be good with depth effect for background blur.
I would recommend you to wait for a while Oppo F9PRO & Vivo V11 PRO is old thing now!!!
And, yes they won't support portrait mode and I think they support bokeh mode which is similar to that but won't perform in most cases.
Oppo & Vivo handset are not that tough.