i have not used a belt in anything for years now, until i recently got into the PLifting side of things and watched videos, every video you will ever watch of lifters doing maximal or near maximal, they all have a belt on , speaks something.
Oh yeah I threw a belt on legday the other day = new squat and DL PR's by 50lbs a piece.finally over 500 in both
so that says something, helped me stay tight in the bottom on squats, something to drive against, and helped my back in DL
you have to do your core work still , but i am sold.
as far as straps go , i havent used them in a while, i think they have there place i.e. heavy db bentoverrows, shrugs etc.
not DL's though just imo