US motors cannot lift as much, are not as reliable, and cost more.
The upcoming Russian Fenix generation of super heavy lift motors surpass all current and future US motors - public and private.
There are no such engines — they plan to upgrade the RD-171 (a dual-gimbal four-engine cluster often erroneously claimed to be a single engine) to be a methane-burner. Before the end of Roscosmos, development was estimated to *start* in 2018.