that's the oneplus 7t pro
https://www.gsmarena.com/oneplus_7t_pro-review-2008.php
the regular 7t is an equally good phone. the 90 hz display on some oneplus models is something special, you have to see it before buying anything else.
as for huawei, i never liked emui, so no matter how great the hardware is, i can't wholeheartedly recommend it. camera and battery life are great on the p30 pro though.
xiaomi's miui is a lot better than emui, but if you're willing to spend for a oneplus, and camera is not a huge priority, there's no point in getting any xiaomi over a oneplus.
as for the samsung's, the new one ui is actually quite nice with the redesigned menus, the dark mode and some less bloated default software too. after 2 xiaomi's, i bought a samsung for the missus, and she's been enjoying it. the flagships have a very hard task competing with oneplus, though. ip rating, sd card slot and headphone jack are fine, but battery life isn't that great on any s10 unfortunately, and they can't match the snappy oneplus performance either. also, samsung used to be the undisputed king of displays in basically any price range, but that's not the case anymore. 90 hz is the flavor of the year.
one general remark: 5g is already available in some countries and will become widespread in no time. if you want a future proof device, you might want to consider 5g too. in that case, you have to check what's available in your region. for instance, there are around ~20 5g models on the market, but for me, the lg v50 5g, the samsung note 10 5g and the xiaomi mi mix 3 5g are the only available 5g phones with a proper hungarian warranty. so there's that, too.