When I was much younger (18-20) I had a program that used both, after pulling sumo my conventional would always go up and vice versa. I wouldn't do both in one workout though unless that was all that I was doing for that day. I really wish I had a copy of that program, I went from 420 to 585 in about a year of it.
I like conventional but lately i have been liking the way SUMO hits my glutes and inner thighs. I do them after my squat routine and it feels like every muscle is completely worked. I am sure I will go back and forth just like everything else......
learning either takes lots of time..... one workout won't be much of an indicator which one works better for you. I pulled conventional when I started and topped out at 600ish in a full meet.... 635 in the gym.
most of my team pulls sumo so with the help of some of the best sumo guys in the US ( won't name names on here, but a few guys pulling over 800) I took a year to get used to sumo and hit an easy 606, missed 640 that year on a close 3rd attempt. 650 in the gym.
After figuring out that I'm not built to pull sumo my coach made the call to go back to conventional I put in some work on my weak points and pulled ~700 in a meet.
There's no one best style. Even after getting a pro total and a PR pull with a conventional deadlift I still work sumo to strengthen my hips.