So I have tested these both quite extensively and notice no significant difference...
Both have same amount of stamina reduction so no difference there. Craft Speed is slightly better on the steel anvil (no biggie as late game crafts take so much stamina the speed isnt what caps you its the stamina drain)
Quality - avg quality of 100 iron pick axe crafts lvl 40 on the iron was 101%, avg quality on 100 pick axes on the steel anvil was 103% lvl 40 also.
At 50 steel ingots to craft I just dont see any reason to craft a steel anvil... Can anyone enlighten me or are they just not balanced yet?