That's odd, I thought the consensus was that Angel's last season was its strongest.
The majority opinion I've seen is more along the lines of "season 4 is crap, season 5 is good but not as good as the first three" which is about right.
That's certainly not what I've heard. In fact, most people I've talked to, even here on this board, consider Season 4 to be the high point based on it's tight, serial storytelling.
Season 5 overall is probably not quite as good as Season 3 but I'd definitely say it ranks above Season 2 and especially Season 1.