- 'Bangel is a forever love'
This seems like a lazy meta-comment instead of looking at the characters actions during the shows. You could say maybe from Angel's pov (if we completely ignore Cangel, and why wouldn't we?) because his future and overall emotional development is somewhat stunted by his manpire-ness and curse condition. And even then he made lots of progress and built himself a new life and family entirely away from Buffy.
Angel's 'one day I'll shanshu and be with Buffy' doesn't feel like a love story, but a retirement plan; 'this, then that'.
With Buffy, she always seems to be hopefully searching for something to be like what she had with Angel, which suggests that she might want to replace her 'forever love' with something more here and now and fulfilling and great. Good luck to her I say (show Buffy obviously, not comics!Buffy, comics Buffy is a broken character)
Overall the argument is cliche because it seems very static, stale and not the stuff of interesting storytelling.
- Bangel was just 'puppy' love; immature and not real. But Spuffy was 'real' love; adult and messy.
Firstly, way to be completely dismissive of the main characters unambiguous emotional declarations before then saying that later on a super-depressed and traumatized Buffy is 'obviously' in love with Spike because of a look or something lol.
And secondly, nope, neither was real love, as in 'realistically depicted' love, both were totally melodramatic in their way. You want to look at semi-realistic relationships in the show then Buffy's undead beau's are not a good example. Look to maybe Buffy/Riley (at a massive stretch) or one of the Scoobies and their love interests; those were made up of more little sweet moments. Real love is often more like that.
- 'Angel never really knew Buffy, Spike understood the real her'
This well-tread argument often blows my mind; on the show Buffy was never more emotionally open and real and honest with anybody than she was with Angel. She talked with him, confessed and discussed with him; everything about her personal life and her fears and many neuroses; really, a lot of yammering occurred on her part. Angel would listen intently (not really a big talker) and then give advice or just some comfort. He knew her because she talked to him about herself.
With Spuffy their communication was awful; incredibly terrible. Punch, punch-snark-kiss-unwanted declaration of love-got a soul for you or whatever.
Spike never knew like, the basics of Buffy's struggles and fears, he just projected onto her an awful lot. What we tended to have with Spuffy was 'Spike and his insights' where Spike would say 'Buffy, you are this, because this', and most of the commentary was just way off the mark more times than not. It gives the illusion of knowing without actually giving us a true picture of closeness.
On the flip-side Buffy always wanted to know more about Angel, wanting to share together (and yes, its kind of a problem with their relationship that he never really did), but Buffy wasn't really interested in knowing the 'real' William, especially when he got a soul.