Under 2k , Sound Magic PL-30 / E30 would be your best option for upgrade if you love mids and soundstage . But coming from ES18 the bass will be much much lesser . Detailing wise it will be a huge upgrade. Other options you can consider is E10 or Brainwavz M1 as well . Both have pretty neutral sound with good / average soundstage.
You could also go for a used M2 Or Signature Acoustics C-12 but both are on the heavier side of bass but overall much better than other sub 2k options in terms of detailing and clarity. M2 has more congested sound compared to C-12 , both have almost similar amount of bass , C-12 is more laidback / warm sounding and suited for instrumental etc compared to M2.