Basically AP stat or seminar, or take leadership which is a class required to be president of the class of 2018 at my school?
it totally depends on what other AP classes you will have taken or are taking or planning on taking.
Im planning taking APUSH AP Lang, AP Chem, Math analysis honors, and A sport but my last period isnt decided yet.
Replace “a sport” with a language and take Leadership since you already have a math class (Math Analysis Honors).
Leadership for sure. Being class president is far greater an accomplishment than taking an AP course, particularly AP Statistics, which is known as an “AP lite” by colleges. And I second @MYOS1634’s statement about languages–they’re very important.
Okay, because Im planning to go to a UC so do you think 3 years of a language if ifne?
yes. 4 is better, but 3 is okay. Do you have an art class (required for UCs)?
Also, Leadership is better han stats based on your overall profile 
Don’t just apply to UCs though, remember to include CSU’s and perhaps some privates (URedlands, Chapman…)
Since you most likely won’t be president, take AP Statistics
Yeah I took Jazz band in 9th grade, so that counts as an art right?
Check with your guidance counselor.