Erangel is the original map of PUBG with a standard size of 8km x 8km. With large hills and the vast distance between cities, most fights in this map are in the medium range, which is the optimum range for DMRs. DMRs are somewhere between Assault Rifles and Sniper Rifles with have high damage stat while having better fire rate than sniper rifles. They are the perfect weapon for long fights or shooting a running target from far away.
Based on the statistics of 100,000 PUBG matches, here are the 3 most effective DMRs on Erangel, Mini 14, SKS, and SLR.
According to GOSU.AI stat, on average in a match, there are 205 shots from the Mini 14, 155 shots from the SKS, 64 shots from the SLR. The Mini 14 also deals the most damage with 856 per match, followed by 740 damage from the SKS and 331 damage from the SLR. Funnily enough, while the SLR has the highest damage per shot out of all three DMRs, it deals much less damage on average in a match. Probably because of its low drop rate on Erangel combined with the high recoil that people don't use this weapon very often. When compared with the Mini 14 and the SKS, the SLR came out much later, which is also a reason why people prefer the other two.
There are two other DMRs available on Erangel, which are VSS and Mk14. However, the VSS is just too weak due to low bullet velocity and damage. Mk14 has insane damage, however, it has high recoil and it's an airdrop-exclusive weapon.
That being said, everyone has their own preference. For example, if you feel like you will do better with the SLR, you should just use it instead of forcing yourself on other weapons.