r7 vs r8

Good day, I just ordered Canon EOS R7, with 18-150 STM, and considering to buy the Sigma RF-S 18-50 2.8 as well. Later on might add EF-S 55-250 STM or the RF 100-400 STM. After checking this option against the R8 with RF 24-105 4-7.1 STM and RF 100-400 STM. I was tempted to go FF with R8...