I'm closing in on fifty years in Olympic lifting. One thing that's seldom mentioned in discussions of it on this Website is just how flexible you have to be in the shoulders and hips, unlike powerlifting, in which, as Professor Squat Freddy Hatfield pointed out years ago, a certain amount of tightness in the hips and shoulders is actually an asset. If anyone's having trouble locking out the jerk, it's likely from either or both of two causes: either the split or squat is not low enough, and/or the lifter can't roll his shoulders back enough so as to catch the weight a little behind, and not directly over, his head (Girls, I'm not ignoring you when I use the pronoun "his," referring to the lifter. If you do jerks as part of your workout routine, the above applies to you, too).
Finally I'd say, learn both styles. There'll come a time when your heart and mind, as a friend of mine recently put it, say "Split!" but your joints say "Squat!"
To determine whether you're flexible enough in the shoulders, here's a suggestion:
Get inside a squat cage. Set up the safety bars so that they're at a level just over your head. Put an Olympic bar atop the safety bars, and put just enough plates on either end (think safety! WITH some kind of locking or spring collars) to give you a little resistance. Grasp the bar with the grip width you normally use in pressing, squat down just low enough so that your arms are locked out and you're facing forward as you would when you're about two thirds or even three quaters of the way up from your split or squat. Make sure your feet are evenly planted, with the bar in that position slightly behind your head, as I described above.
Stand up, with the bar locked out.
If the bar feels like it wants to fall forward, there's a good likelyhood that you have shoulder flexibility issues.
If the bar feels like it's falling into a "groove" (that "groove," BTW, shoud "feel" VERY stable), then your shoulders are likely OK, and your lockout problems may be caused by fatigue. It can happen.
If you practice any kind of Olympic lifting with good form, you'll get to the point where both the snatch and the clean & jerk will feel like they're almost pulling you up out of the low positions. If you have to fight your way up, you may have flixibility problems, or you may have caught the weight at the very edge of that "groove," or you're setting a PR.