Personally I think the initiate feats beyond warlock are kind of a waste. You only get a single spell from a list that isn't super impressive. There are some good utility spells like longstrider and jump, but as a ranger you have access to those anyway anyway. Cantrips can be nice, shocking grasp lets you do damage and disengage. Blade ward can be helpful if you know you will be taking a bunch of physical hits next turn. I also like chill touch to disable healing. However with your stats as a ranger I don't think a cantrip will outperform your weapon damage with a hill giant potion.
While I do think warlock is the only initiate feat that isn't a waste, it unfortunately is a waste for a ranger. Hex is really the gem of warlock initiate. In part because you can reapply it making a single spell go a very long way. Unfortunately as a ranger you have hunters mark which is pretty much a weapon damage version of hex that is applied the same way and can't be stacked by the same character. If you really want to pick it still then I would go with hellish rebuke to add a reaction to your kit when you don't normally have one (assuming you didn't pick giant killer).
