I do see the point that the conclusion to s5 was a natural ending for the show, but I've come to appreciate that each season of Buffy has its own unique feel even if you can kind of lump similar ones together like 2 and 3, for example. And the Spike-Buffy relationship was always going to be divisive - which the show occasionally acknowledged - but it fit into the redemption theme well.
Angel - I actually liked s1 as it was clearly meant to be a companion to the lighter-hearted s4 of Buffy (I think the timelines are the same). s2 was very dark at times but kind of a highlight. s3 and s4 have their failings, particularly s4, but s5 had some great, kind-of-satirical material in it and the return of Spike was used well even if it initially felt a bit contrived.