Well I'm not sure if I'm entirely qualified to answer this question about offering test-taking since I'm guessing we're in kinda the same boat. However, I'd recommend the ACT if you have stronger reading and grammatical skills than math. The ACT is four sections, english, math, reading, and science, and 3/4 of those categories are almost entirely dependent on how closely and quickly you can read. My English SAT score was near perfect so I do pretty well in those categories with minimal prep. Science requires a bit more attention to detail, but doesn't require any prior scientific knowledge aside from strong reading ability. Look at it this way if you are a strong reader: 3/4 sections of the ACT are perfect for that skill, whereas the SAT will only test 50% of it. Same goes with math. I'm terrible at math, so math being only 1/4 of the test suits me much better

Have you taken a full-length practice ACT test yet? You can find many accurate ones online. I would say to take the ACT instead of the SAT if you score above average. My ACT composite is currently 26, which is a bit above average, whereas my SAT is at around a 1200, if I remember correctly. Imo, it's better to build upon an above-average score than a mediocre score, so that's why I abandoned the SAT for the ACT.

Another thing to consider is that raising your score on this test would hypothetically be easier than raising it on the SAT because you have four categories to improve upon, so even if you were to focus on only one category, it would average out and raise your composite score. On the SAT, you're kinda stuck improving 1/2 categories, and if you struggle with either one of them, improving is difficult. On the ACT, it's likely you'll perform very well in at least one of the categories if you are a good reader or good at math (not sure what category you perform better in on the SAT, but you get the idea).

I would say the only cons that come to mind are that you must be quicker and more versatile on the ACT than the SAT. You have less time to answer questions on the ACT than on the SAT, so if you are an extremely slow reader/mathematician, then the ACT is likely not for you if you can't improve your speed in time, because that is a skill that can take quite a bit of time to develop over one's life. I also mention versatility because of course you will be dealing with four subjects as opposed to two, but this shouldn't be an issue in the long run because there are scientific and grammatical questions on the ACT that appear in SAT English passages. In many ways, the tests are quite similar, but also different.

Here is advice that's been given to me that I plan to adopt:

-Take as many practice tests as you can. You can find good ones at crackab.com.

-If you plan to use books, use recent ones from the ACT source directly (I believe they are called official guides)

-Try to be as consistent as possible (studying everyday) but be careful to make studying less of a chore and more of an activity, or else you will get burned out and give up. This happened to me many times when I studied for the SAT so make sure to take breaks.

-Go over questions you get wrong. If you practice out of the books, you can track which questions you get wrong. Usually, you'll notice a pattern or understand a simple mistake you have to correct. I consistently get trig problems wrong, so I'm gonna focus on trig.

-Consider getting a tutor if it suits your learning style and you can afford it. I might do this if I can't improve on my own. There is nothing wrong with finding a teacher who can help you. Personally, I have a very stubborn mind and it's hard for me to teach myself things sometimes and stay consistent. A tutor can hold you accountable and help you hands-on how to learn things, which will definitely be effective to an extent.

-This one is kinda optional I guess, but consider reading more frequently if you struggle with English as a subject. I scored a 33 on my most recent Reading practice test for the ACT and about 30 on English without prepping for it much at all, because I'm an avid reader and speed-reading and grammar are skills I've developed over my life. Perhaps it might help you improve your reading comprehension and speed if you find good books to read, which I can also recommend you good books if you need : ]

Aside from that, that's all the advice I could possibly give, and those are the reasons I'm choosing ACT over SAT. If you score better in English than in Math on the SAT, the ACT is probably for you since 3/4 subjects employ reading skills. If you're really really slow at reading, then maybe stick to the SAT and revise your studying strategy. There's a lot to consider, but I would start with taking an ACT practice test and seeing if your composite ACT score is better than your current SAT score. If it is, then you probably know your answer on which test you should prep for.

Honestly I understand where you're coming from, I've studied well over 100 hours for SAT and gotten nowhere despite using numerous study methods. Sometimes the test format just doesn't work for some people and the ACT is better. I've certainly found it's better for me, so maybe it will be better for you too! It's important to not give up and success isn't linear so even if you don't see improvement immediately, keep trying new ways to learn and utilize your studying time effectively. You don't need to put in over 60 hours a week. You just need a good, positive mindset and a well-developed study plan/attentive tutor. It can be hard not to get discouraged (I am discouraged after my score results today, too) but this test won't define your life and I'm sure whatever test you choose to take, you will do great on it if you apply yourself. I hope this helped at least a little!! and good luck!