It depends on your experiance level and your own preferance bro.
Sub-q is safer in the sense that you wont ever have to worry about hitting a vein. But for me (again, probably just because im used to IM), Sub-q is less predictable, the only time i did it, was the onyl time I felt like I was going hypo. Going sub-q can also promote lipohypertrophy (and by definition, going sub-Q is going to a place where you already have fat).
IMs onset is quicker (and to me easier to predict, however most slin vets will tell you that IM is more dangerous, and they may be right in most cases, so dont ignore that warning). And you lower youchances of developing too much (provided you eat super clean, of course).