Is it better to fight on the inside or outside as a southpaw fighter?

[SugarBoxing]

Southpaw are generally more slick.
I would say better put pressure on them = inside
Depends on your inside skill actually

[greynotsoold]

The big reason that fighters are told, in a lefty/righty matchup, to keep the lead foot outside, is to keep the other guy in front of you. But...
The school of thought in boxing has long been that you never give up the inside punching position- not talking about range, but about being inside position-wise, if that makes sense. By keeping your lead foot outside his, you give up the inside position. In essence you take one of your hands out of the picture.
So you pick your spots and do some of both. Of course it also depends what your opponent is trying to do to you, what his strengths are, etc...