more apps or less apps
you choose

android user switch to windows phone will say windows smooth,less app,less mod
windows switch to android will say a bit lag ,much more app,many mod
both phone look smooth to me,just choose a os u like

best you go try yourself la. Our and your perceptive  of lag is totally different. To me lower end android is very laggy.
For me the one android phone i can start accepting is note 2. Anything beside that i feel laggy.

WP7.5 no lag but no real time notification center and no real time multitasking.

The smoothness is iOS phones either 4S or 5

lumia 1320

The s-pen is productive. Beware! Once you use it, its very hard not to have it.

If you're like me just use for productivity, chatting, video and simple games like candy crush then power is of no concern as long you have 1gb free ram and quad core >1.6gzh