Two pins of sust a week, for a first timer would be fine. The only annoying sides you would likely find would be possibly alot more acne and mood swings than you would get with test E. Only because there would be a geat deal of blood level fluctuation.
I cant not recomend sust though, my first cycle ever was sust alone.
Test E would be alot more stable. But either will definatley do the trick.
At your height and weight, I would suspect diet is the culprit in your stops in gaining size and strength.
I'm not trying to discourage you using AAS but post up an example of your diet with macro counts if you would. I bet a diet shift would spark a nice size increase. Also possibly a change in training split AND routine.