While it is true the rewards are lower - so are the rental prices! So this still makes it sort of viable. I like the guide, it is quite helpful. Peakmonsters makes lives so easy in Splinterlands.
Do you ahve any favourite cards to rent without which you feel sort of "incomplete"?
!1UP
It depends on the league, but one thing I always have rented is the creeping ooze! The Slow ability is truly useful, and I'm sure I'll miss it when Modern league comes.