depends on what you are planning on doing, here are some specs that have a bearing on the performance difference between the two.
 
     miller 252, has a 300 amp maximum, Hobart 230 is 250 amps.
 
   millers duty cycle at 175 amps is almost 85%, the Hobart is 60%
 
    input voltage  of the miller is 208/230 or 230/440/525, Hobart, 208/230     
 
    miller has a lot of whiz bang stuff that I don't know if a everyday welder needs  the Hobart is simple and relatively easy to use. but if you are going to do a fair amount of heavy welding(continuous long beads,1/2'' or thicker material) then the miller would be your choice