What is better for phlebitis...asprin, advil or aleve (naproxen)?

See below: All can be used at the appropriate recommended dosage.

Any antiinflammatory: Any anti inflammatory that is best tolerated by the patient will help phlebitis symptoms. However treatment by a qualified specialist for the underlying reason would be best.

That depends: There are two types of phlebitis deep vein phlebitis or DVT and superficial phlebitis. I think your question is about superficial phlebitis, which can be treated with anti inflammatory medication like advil , or my favorite aleve (naproxen). Dvt or deep vein phlebitis [aka thrombosis] should be treated with blood thinners.

All work.: There is no best medication for superficial phlebitis. Any antiinflammatory that is tolerated by the patient is acceptable. The type ordered is usually determined by the physician's training and experience. I prefer advil, (ibuprofen) Motrin or naproxyn. Wet heat to the area also helps and an evaluation by a vein specialist would also be recommended.