Is it just my imagination, or are we seeing in Season 8 a sort of "one upmanship" on Spike by Angel?
Spike always knocks the "Welcome To Sunnydale" sign over when he arrives, so Angel knocks over the much bigger "O" in the Hollywood sign.
In Season 7, Spike only talks to incorporeal images of people who are dead, but in Season 8, Angel gets to talk to real people and dogs.
In Season 7, Spike with considerable difficulty, killed one demon who popped out of the past, but in Season 8, Angel is killing monsters left and right, seemingly without even really trying that hard.
Spike was (arguably) Buffy's only equal as a fighter, so now Buffy and Angel are the only two with super powers.
Buffy and Spike tear a house down with their sex antics in "Smashed,", so Buffy and Angel rip a hole in the interdimensional barrier with theirs.
The "best day of his life" for Spike was when he just held Buffy in his arms and watched her sleep, and Buffy would only say that she was "there with him," but the "bestest day in her life" is with Angel while they're doing their version of "Smashed."
In Season 7, Spike kills a few innocent victims while under whereas in Season 8, Angel kills, or is responsible for, the deaths of of literally hundreds, if not thousands.
Spike helps Buffy's little band of Potentials fight the Bringers and the Ubervamps, so Angel is helping Buffy fight gigantic super powerful interdenominational monsters.
In "Chosen," Spike's scent is on Buffy, and Angel seems to be only irritated and suspicious about it, but in Season 8, Angel's scent is so strong on her that she has to shower in order to not be offensive to Spike.
Buffy sends Angel off to form a "second front," which is never needed, in "Chosen," but in Season 8, Angel, for all effects and purposes, IS the second front, and it is integral to Buffy's battle plan.
Of course, as a POSSIBLE plus on Spike's side,
Angel showed up at the last minute with a little bitty amulet, whereas Spike shows up in the Buffyverse version of the Beatles' yellow submarine (crewed by giant beetles, I might add), but so far we don't really know just how important it will be in the upcoming battle.
In Season 7, Buffy only accuses Angel of acting childish, whereas in Season 8 he admits that he's immature.
As I say, it may just be my imagination, those might all just be a whole lot of coincidences, but here's something to consider:
In Season 7, Spike died protecting the world. Carry my theory to its logical conclusion, and we might be seeing Angel die to save the universe.