Jelco SA-750D or Rega RB250

Audiomods Classic II. The British designer/builder uses the best Rega arm tube (only), machining all the other parts himself.

Jelco 750 easily.

I have mounted both on my Sl1200mk3 with custom armboards.  Yes, the Jelco just looks and feels like a better made product.  It tracks well and works great with MC carts.  I love mine.  The RB250 is not very adjustable, mounting and aligning is more of a PITA but with right cart, it sounds fantastic, even with the stock cable. Something like a 2m blue or older Shure carts that I have.  So, it all depends on the carts you want to use really.  
Btw, replacing the Jelco mounting collar is a must.  If you tighten the set screw on the stock collar, the arm pillar will tilt and the stylus will not follow your desired alignment arc no matter what!  Easy to spot by placing a spirit level on top of the fluid reservoir cap.