[emiljbs]

First of all: A wide stance low bar back squat going down to parallel together with conventional deadlifts will strengthen your hamstrings and glutes greatly. There are reasons to pull sumo, those reasons are mainly proportion-related. Most people I've talked to who pull sumo at meets usually also train using the conventional dead lift (see for example Dan Green).

Second of all: I'm going to assume that your pelvis suffer from an anterior tilt. If so, then focus more on stretching your psoas muscles since these are usually very tight in people who sit down a lot (and you browse HNews) and pulls on your pelvis. Strengthening your back, hamstrings, glutes and quads aren't a bad idea either, it's just that these are things that usually come with a good training program.

https://en.wikipedia.org/wiki/Psoas_major_muscle

Third of all: The position that is toughest for the lifter is largely dependent on the lifter's own weaknesses. I, for example, deadlift conventionally and have the most trouble to come off the floor because I usually do touch-and-go DLs.