Yoma 2b - Sukkos has many mitzvos

The gemara suggests that Pesach might be the festival where we'd separate the cohen gadol for a week, because it is always listed (Rashi) as the first of the yomim tovim. Or maybe it's Sukkos, because Sukkos has many mitzvos (Rashi: sukkah, lulav, aravah, nisuch hamayim).

It seems clear from the gemara that this must be an advantage that Sukkos has over the other festivals, just as Pesach has the advantage over the others that it is listed first.

But it seems to me that Pesach has even more mitzvos than Sukkos! Korban pesach, matzvah, moror, hagadah, and the isur of chametz?

I don't know if we're counting actual mitzvos from the taryag; korban pesach has like a dozen, and chametz has about half a dozen in the Rambam. Maybe issurim don't count, only mitzvos asei? Or korbonos don't count (but nisuch hamayim is listed). And the Rambam doesn't list maror separately, just part of the mitzvah of eating korbon pesach. Anyhow, I'm not sure how to get Sukkos to have more than Pesach, and even equal numbers wouldn't work in the gemara.

Followup on this: I notice that for the rest of the gemara, we are going to be trying out various possibilities (Atzeres, Rosh Hashana...) without bothering to give any reasons why they are especially chashuv (the day the Torah was given...). Not sure why we stopped. Perhaps here the only reason we need to give reasons is to deal with the initial objection, וכי תימא לא ידעינן הי מיניהו - meaning, we can't justify distinguishing the regalim, and must bring all of them. So the answer is, No, maybe it's just Pesach, for this reason; or maybe it's just Sukkos.
Afterwards, we may not be as bothered with all the various other yamim tovim.

My chaver R' Pesach S. suggested another possible answer: Maybe we were still trying to do regalim when we got to Shavuos next. At that point, it is the last one standing. After Shavuos, Rosh Hashana is the only possibility left, not a regel.
According to him, we never had to justify trying everything out, only why we tried this before that.