This is just a quick summary of what I've read that drove my decision to buy a 4WD with locking diffs both front & rear. I also decided against the CVT in favor of a clutch and 5-speed transmission (similar to a car). If you're looking for a 2WD UTV, then it won't make much difference. I wouldn't consider taking one of these into a situation where I might need a locking diff. I personally would want a 4WD with both front & rear locking diffs independently selectable. I want to have the option of having all four wheels available to get me out of trouble. But even 4WD with full lockers won't guarantee anything. Most prefer rear lockers because lockers on the steering axle leaves a lot to be desired on soft sand or dirt (tends to not go in the direction you want to go).
Front lockers are on UTVs that are FWD; rear lockers are on UTVs that are RWD. Again, it's a matter of preference whether you want FWD or RWD. Most are RWD. Unlike cars, I don't know of any FWD UTVs.