Personally, I like Livaan, Cultist of Tiamat quite a bit since having Prowess triggers rather than spellslinger triggers always increases the number of potential triggers considerably. It pumping other creatures also allows more evasive threats to benefit from the bonuses.
Erinis, Gloom Stalker also has decent stats for its cost and a potentially rather powerful if a little niche effect.
Alora, Merry Thief can easily be good so I would at least consider her. Also pseudo-support for ETB matters and ninjas/saboteurs.
But yeah, I am not a fan of Initiative and (other) dungeon delving mechanics.
Something that I have been asking myself since the Thriving Gate lands were leaked: Are these better than Terramorphic Expanse? Terramorphic gets your choice of a single color and has landfall/delirium/graveyard synergies, but the Thriving Gates gets your choice of a single color PLUS the second color they are fixed too.
I asked a friend this and he said "it feels wrong" to cut Expanse, but I think it would be okay to do so, barring heavy synergies from Expanse.
I finally cut Phyrexian Rager for that reason the other day. For years it held its spot on raw power (as opposed to synergy with any given archetype), but with cards like Cloudkin Seer and Inspiring Overseer, it just doesn't cut it anymore. Swapped it out for Morbid Opportunist and have been really happy with the change.
Noble's Purse is a nice Sphere of the Suns variant, but until there are more artifact/treasure payoffs in my cube, I'll continue to run Sphere since it'll cut down on the number of "let me go grab the token" gameplay pauses.
Also, I really want to like some of these "Choose a Background" cards. Lulu, Loyal Hollyphant is another payoff for UW blink, and it has cross-applications in GW counters and Wx aggro. Wilson, Refined Grizzly is probably the best "Bear" ever printed that is an actual Bear. I've made an exception to functionless trinket text like this before for Halana, Kessig Ranger, but "Partner" seems easier to ignore than "Choose a Background" or things like the Bolas planeswalker text on Wasp of the Bitter End. Though, if these cards prove themselves in other people's cubes, I may change my mind.