First, I assume you are talking about laser or GPS. Both types are rangefinders, in that they tell you the distance from your position to some other feature on the golf course. I've owned more than one model of both, and I now stick with the GPS. However, functionality depends on what GPS or laser you choose.
GPS - the lower grade ones only give distance to the green, often only front, middle and back. They don't tell you anything about bunkers or hazards. The better ones like my Garmin Approach G5 give you a graphic representation of the hole, give distances to many features on the hole to help you plan your strategy for playing the hole. It has a touch screen which allows you to place a target circle anywhere on the hole and get the distance from you to the target, and from the target to the hole. You can move the flag around on the green to place the hole in it's approximate location for the day of play. It will also track several common stats and keep score for up to 4 players.
The cheaper lasers sometimes have trouble picking up the flag from beyond 150 yards, the better ones do a very good job of this, but I still seemed to get bogus readings now and then. it was hard to trust it implicitly. It is also strictly line of sight - it can't see through trees or over hills like a GPS can. Also consider that some lasers come with the ability to measure or estimate slope (elevation change), and those units are not allowed for competition or for handicap play, even if the slope feature is turned off.
The better modern GPS is a better all around tool for the average golfer. The laser is more precise when you have line of sight to the target, but you have to ask yourself, is +/- 9 feet close enough (the rated accuracy of a GPS - in actual use they are usually closer than that), or do you need the +/- 3 feet of a laser, and can you sacrifice the other advantages of a GPS to get that additional 6 feet of accuracy.
After using both for a couple of years, I ultimately chose the GPS because it gives me more information, and more overall assistance in planning my play of each hole. It makes planning and playing layup shots easier, gives me accurate distance to the hole as well as distances needed to lay up short of or carry over bunkers and hazards. I can measure to landing areas around doglegs and over hills.
I don't know what your budget is, but whichever you choose, don't cheap out. You'll be happier in the long run if you get a full featured unit.
"Your proper place on the course is directly behind the group in front of you, not directly ahead of the group behind you."
Titleist 913 D2 10.5° Driver
Mizuno F-60 15° 3W
Bridgestone J36 22° & 25° hybrid
Titleist AP-2 5I-GW
Titleist Vokey 54.11 SW
Cleveland CG15 56.10 SW
Golfsmith Enterprise putter
Last edited by Fourputt; 02-10-2013 at 10:01 AM..