New player, wondering what the best farming runs I should do for coins?

Basically as the title says.

Right now I've been doing higher tier runs more often versus lower tier longer runs.

Looking over the runs it seems clear at my current progression that I get more from shorter runs.

I'm still very new and havent gotten past 1500 on tier 1. But those runs give me significantly less than running t7s where I die around round 600.

I've got the Golden Ultra tower too luckily.