Since Samsung had an android exclusive. meaning that more android phones and less Wps which has now ended because Google has got Motorola for their nexus phones. which basically means Samsung is left in the dust while fighting apple. to avoid this Samsung should shift a quarter of their focus to Wp8. while Nokia is MS's nexus lineup. MS would gladly help them in the fight with apple. if Samsung helps this would help Windows phone in general. With Nokia's very good hardware and pureview and Samsung high specs and hype. this could be a positive effect on Wp8. since Nokia and Samsung want to get to the enterprise market.

Samsung's phones = for people who are used to samsung phones and want a S3 like phone with MS ecosystem

Nokia's phones = for people who want to exclusive apps, good looking hardware and want the top of the line pureview

as for HTC since they are loosing money to Samsung and starting to loose in the android space. since MS is their second OS partner. and HTC is loosing money in adroid. they could do more focus on Wp8. they used to be the dominant OEM in wp and now Nokia smashed them in that space. HTC knows that they can't compete with Samsung. so HTC second option is Wp8 if they put focus in Wp8 it would turn out better than their One series phones.

HTC phones = people who like the One X feel and also the HTC hub app.