California, by far. for all the reasons previously stated.
one thing you left out about diversion is that, once complete the offense is wiped off your record. so essentially as long as no two offenses are comitted while one is being worked off. every offense is a "first offense".
thats if you are actually convicted, 90% of the time the cops let you off on the spot with a lecture. and im speaking out of experience with drugs "other" than pot. i dont think ive ever seen anybody actually get in trouble for anything pot related (i live in SF bay area). its decriminalized almost everywhere so unless youve got some ungodly amount and no cannabis card, and your stuck in some weird ass situation u cant talk your way out of... i dunno.
alot of poeple here have cannabis cards, and those who dont usually know someone who does, so whenever i get pulled over with an amount over an ounce i usually say "i just drove my friend to the club to get his medicine, and he must have left that bit in the car". then they usually wont even take it, at most they will run the name of the person with the card and if it checks legit they'll let you go.
if you live in california and you arent already getting your weed from a cannabis club, a good idea is to "store" your weed in a club bag, you know those big silver capri sun looking bags. with the club sticker still on it if you can.
p.s. when i did diversion it wasnt even informal probation, it ended up being 30 hours community service. and i had over an ounce of weed, a scale, money, bags, and a cell fone. i told them id do it at my school. they give u a form for signitures, i forged all of them and turned in the paper, they didnt bother calling or checking any of it. that was it, and it really did get wiped from my record.