Which treatment for varicose veins leave less pain and discoloration of the skin?

Depends : Size of veins, techniques, bleeding factors, skin status, all are intended to be cosmetic to a degree. But it varies, .

Phlebectomy: Phlebectomy to remove large, ropy vv will result in bruising, which resolves in several weeks, and is quickest way to see results. Sclerotherapy is performed a lot in european centers; phlebitis is common, resulting in pigmentation, requiring drainage at times. Important to obtain ultrasound, and ablate incompetent axial veins (great/small saphenous) along with phlebectomy.