You can look at the bottom of Bava Metzia 30A that a Kohen who can return a lost object but will become tamei (impure), we do not say that we can override the negative commandment between the Kohen and Hashem (to not become impure) because he can return a lost object (between man and man). Now it does appear there that there is a positive and negative commandment to not become Tamei. Perhaps if it was only a negative commandment he would.
Nevertheless, the Meshech Chochma (Vayikra 19:4) says that one could not consider the idea that a mitzvah between man and his fellow could push off one between man and Hashem. Honouring your parents needed to be taught does not take precedence over Hashem because part of honouring your parents includes honouring Hashem, but still it cannot override.
The Chasam Sofer in Sucah 42A says that one could not consider overriding a mitzvah between man for Hashem, like stealing to do a mitzvah for Hashem. Only a negative against Hashem can be overridden by a positive Mitzvah for Hashem.
The Shav"T Shem Aryeh (in siman 64) explains that mitzvot between men contain also an element of man and Hashem since he commanded it, but man and Hashem don't contain an element of mitzvah between men. And so one is more categorically obvious to not push off the other.
In Summary, we saw with the Meshech Chochma and Chassam Sofer that only mitvahs of Bein Adam L'Makom can push be "traded", ie: a positive override a negative. So clearly a positive of one cannot override the negative of the other type.
What about two positive mitzvot?
We don't consider one "more important" than another. See Pirkei Avos 2:1 "And be [as] careful with a “light” Mitzvah as with a weighty one, for you don’t know the reward given for [each of the] Mitzvoth".
Usually when considering Mitzvahs there are a number of considerations like, the time limit of one mitzvah ending before another, if one occurs more often, or will one be a negative prohibition. There might be a few more, but I have not seen the idea that one should do mitzvah A over mitzvah B because it was one class or another.
In fact Rashi at the beginning of Parshat Mishpatim says that the monetary rules were given on Har Sinai like everything else, imo equating the mitzvot. Similarly the ten commandments were given together and even said at the same time, likely to show the equivalence of their status.