Pretty much everyone I've talked with or heard about via Internet or real life has preferred subq over IM. The only single person who didn't like it was because he compared his peaks IM vs. subq and found his total T a few hundred points lower with subq, which is erroneous reasoning for two points: subq has generally lower peaks and that's one of its big advantages -- it trims down the peaks and raises the troughs, making the pharmacokinetic profile much smoother, which means fewer symptoms (notably E2 and everything that goes with it); the other is that subq tends to metabolize considerably *slower* than IM, so comparing your expected peak days for subq using your peak for IM isn't fair at all: things will be slower to reach the trimmed down, flattened out peak for subq compared to IM, so this person should have waited another day or so.
Subq is also ridiculously easier. The big sell for me on this point is that I didn't have to aspirate. I hated aspirating, and there was always a completely irrational man in my head when I aspirated that said I didn't do it right, that I'd inject into a vein, have a heart attack, etc. Subq, for me, stings a bit more, for up to an hour or two afterwards when there's pressure to the injection site. But you can get around this by finding a clever injection site that minimizes pressure.
Not only this, but the big three of TRT prefer subq, and at least two of them use it on themselves: Crisler, Shippen, Marciano. Shippen actually was nastily against IM injections in his book on testosterone from 16 years ago (great text otherwise), but has since changed his mind big time after trying subq on himself and his patients. Crisler said a considerable number of his patients have gotten off an aromatase inhibitor entirely because their E2 levels lower out.
How high your T level goes with subq depends on the person (and, obviously, pertinent variables, like SHBG). Some people have to *reduce* their dose of T because it shoots up so much after a few weeks. A good number keep it roughly the same. Only a few I've read needed to up their dose, but they're probably committing the same "subq fallacy" mentioned above with the one person against subq.