It depends on what you are trying to do. VXX fell out of favor when they screwed up a few years ago, so lost its luster. As a replacement to VXX, UVXY is a near (possibly superior) product with a 1.5X leverage to that of VXX and is behaving (following its mandated operation). For going short IV, I trade options on VIX, UVXY, UVIX (less lately), and SVIX (an inverse which follows 1X SHORTVOL instead of UVIX which follows 2X LONGVOL). I would guess that most everyone that trades these products has their own unique spin.