Depends on what your main intention for the winch is as well. For a mud bogger or typical off roader, you probably want it higher. For recovery of other vehicles, then either a lower mounted or higher is fine. It's really for ease of accessibility and cleanliness. I've had a couple winches and whether it's on top or under the bumper made no difference as far as performance. However it's mounted, you just want a strong and sturdy mount. Usually it's cheaper to go with the lower profile mount or if no modifications want to be made. I think the higher mounts with custom bumpers and a solid mounting system is the ideal way for most people, especially for heavier vehicles, and has that cool look to it, but for a just in case kinda thing to use once in a while, the lower mounts using a hitch type receiver or the like works fine, especially on light pick ups. That's what I did for my Dakota and it works fine. On my '97 Dodge Ram I had years ago, I welded some steel to the frame and fabbed some brackets to bolt to the brushguard where I bolted a Warn winch on. I wish I had pics for that one but that was 15 years ago so flip phones were the new thing, lol.
I forgot to mention, one thing a lower mounted winch can do well, if you don't have a rear mounted winch, is to be able to rig the cable and winch backwards without the cable hitting the underbody of the vehicle. I've done that once just for the hell if it and it worked to my surprise, doesn't pull down so hard on the front end if you have a shorter lead to a snatch block.
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