The two Meridas are almost identical except one is a 9-speed with a headset I've never heard of. Their listed weight is the same. The 9-speed has slightly higher gearing, which would be more useful on the road and would handle any trail you would be likely to ride.

The GT gets my vote because it seems to offer everything the better Merida does and is cheaper ... plus GT has a stout reputation, and I am not familiar with Merida. Could be Merida makes a far better bike ... I know nothing of bike markets outside the U.S. so I cannot say. All three bikes would likely weigh over 30 lbs ready for the road.

The Meridas come with 29-inch wheels which people tell me are better if you are risding off-road on rolling trails and not cutting a lot of tight corners ... what I hear is they will let you roll over stuff you would have to slow down and treat as an obstacle on a 26" or 27.5 bike. I have never tired one. I have a friend who used to race MTB and he is absolutely sold on the 29ers for off-road use.

For road riding the 29ers might make for smoother riding but really, the difference is slight, I'd guess. If yo get a sopare set of wheels, you could mount regular road tieres (700c) on the 29er wheels i've heard, and have slicks for pavement and knobs for the trails. But I don't see you buying a whole 'nother set of wheels.

All three bikes use the lower end of Shimano's MTB drivetrain line, but none of them are bad. The better Merida has better derailleurs by one step.

The more expensive Merida says it has mechanical discs, which people have told me are not as good as hydraulic, which the cheaper Merida has. However, the specific model cuold mean as much as the type---if that mechanical system is better than that hydraulic system, generalities don't matter. (I have only used hydraulic, but don't know enough to compare.)

If I knew anything about Merida I might be of some use. Because I don't I would personally get the GT, but I might regret it later.