for ranger there are very little non-500 buttons builds, basically just explosive shot - but that one works well, can do endgame maps easy, not so good for any kind of bosses than map bosses though
for merc idk
i got my ranger to t15 maps with like 1-2div worth of gear, with plenty of room for upgrades, its pretty easy play, u can stack movement speed on nodes, very high evasion, very big aoe clear at level 90 when you start to get spare points for aoe nodes, incredible clear if you can afford 4th ascendancy carry and 5-6 link