you're insisting on taking matriculation or you don't mind choosing other pre-U course? there are other options like A Levels, Form 6, HSC, SAM, etc. since you said you're interested in designing/architect (your final decision?) there are foundation courses offered for SPM leavers.

<whether or not the foundation course is good, that's a different story>

in order to have better chance at applying to any local universities for design/architecture, focus on these subjects: BM, BI, MATH, AddMATH, FIZIK, REKACIPTA. if u're good in arts (although u didnt take it for SPM), u should start ur folio (a collection of artworks), preferrably one that illustrates a wide range of skills that u have.
applying to local public univs, u will need either matriks or STPM or A-levels. the choice is up to u. u can also opt for diploma right after SPM before continuing with ur degree. it's a matter of choice, really. with a diploma, u will skip the STPM/a-levels exam as well as going straight to 2nd year degree. u might only waste a year, but with a better chance of getting into the degree as u have spent longer doing design/architecture rather than STPM or a-levels.
applying to local private colleges, it's either STPM, A-levels or their own pre-degree foundation courses. these courses take about a year, and usually conducted by the college offering the degree. however, these foundation courses arent interchangeable. meaning, u cant use LUCT's foundation to apply for taylor's degree.
design wise, each school has its own strengths and weaknesses. u need to do a little bit of homework. for architecture specifically, public universities fare way better than private schools, and they are better equipped and internationally recognized.

if u have the money. sure.

i'm not sure how it goes now, but some private colleges still require u to pay for atleast half of the fees even if u decide to quit after a week or two. do check first.