You should have been offered admission to Merced which has a ME major that is ABET acredited. See http://www.latimes.com/local/education/la-me-uc-guarantee-20141225-story.html#page=1 Go to Merced if they offer you a place in the engineering program and not just general admission to Merced (eg. undeclared major)
Otherwise, CC is a better route to a UC than a CSU. Kids from a CC are given priority because its the only way they can earn a 4-year degree. If you go to Pomona, count on graduating from Pomona (its a pretty good program, BTW)
Choice of CC is a tougher choice. It is true that SMC sends many more kids to the UC system than LACC, 1,061 vs 112 according to http://www.smc.edu/StudentServices/TransferServices/Documents/Transfer_Statistics/2013-2014/2013-14_transfers_to_uc.pdf The tough question is what do these numbers mean. Students are not randomly assigned to attend these schools, and you know the area around SMC is much wealthier. More informed parents, expectations of hard work, better high schools, lots of other factors mean that kids in more affluent areas do better in education. To the extent that these factors explain the difference and not something SMC is doing, going there will make no difference. There is no real magic in admissions, secrets that SMC “knows”. Get a good gpa and you’re a good candidate. Nor do they have special ways of teaching that are more effective. So its hard to find institutional differences that explain the different outcomes. I believe, however, there is truth to the argument that if you’re around more motivated kids that rubs off, and if you’re around kids that look down on kids that study or ask questions in class that has an effect too. But its a tradeoff. If it takes 1.5-2 hours a day commuting to get to SMC then the time lost from studying will probably hurt more than being around a better student body will help.
The most important thing, regardless of whether you go to a CC or 4-year, is what you do. Develop good study habits, probably 5-10 hours/week on each class; reading, doing homework, doing extra problems. The latter is important to really learning the material and doing well on tests, yet many kids never do it. There are books for many science/math classes like the “Calculus Problem Solver” with thousands of worked problems so you can keep practicing until you are consistently solving problems, and then the tests in class will be nothing more than what you’re already successfully doing on your own. There is one recent book about learning I strongly recommend you read that talks about effective strategies, called “Making it Stick”