So I'm going to risk sounding like a broken record here....
I don't hate lean bulking. I think it has its place....that place being that it's good if you are approaching your "natural limit"(if such a thing exists), or you're really close to your goal physique but you're not quite there, or if you're competing year round, or if your goal is to gain strength but not get a whole lot heavier. BUT, from the sound of things(and correct me if I'm wrong), you're looking to fill out your physique and you have a bit of a ways to go.
If you "lean bulk", you're realistically looking at gaining 5 pounds of LBM in the next year. I think you know that 5 pounds of LBM isn't going to give you the physique you really want. In fact, I can TOTALLY picture it...a year from now you'll be posting a picture almost identical to the one you did today except your arms and chest are slightly bigger...you'll still complain about feeling skinny and having a small upper body and you'll again want to lean bulk your way to what you really want. You keep it up and you'll probably get the physique you actually want after 5 years or so(assuming you never get injured or have a set back).
If you say fuck it and proper bulk and eat like a champion and lift hard as fuck for the next year, you could realistically pack on 15 pounds of LBM and be a HELL of a lot closer to a filled out physique a year from now than you will if you lean bulk. Sure, you'll be fat for a fall and have fat face and none of your clothes will fit...but please believe me when I say it's worth it.
Cliffs: if you're close to your goal physique...lean bulk. If you're not...break out the peanut butter and go wild.