Just some 2-cents worth re: Marvel vs DC...
1. More often than not, the fights seemed like a rush job (eg, Silver Surfer vs Green Lantern). The best ones IMO: Spiderman vs Superboy, Batman vs Cap America.
2. While some outcomes were in-house determined (eg, Thor vs Cap Marvel: not bad, if taking the above point into account)), others were voted in by readers, and therefore, IMO, simply not acceptable (eg, Storm beating Wonder Woman).
3. The premise was interesting, though I understand the Brothers have been retconned since then.
4. Overall, I like Marvel/DC crossovers (they're pretty much all I collect these days), and whether you agree with the outcomes or not, my feeling is one day these comics may be worth something.
Marvel Vs. DC 1-4 - 5/10
Universe X Vol.2 9 -never read
Blood Rayne- same as anbove
Ultimate FF #4 - 7/10 though can't remeber the issue that much
the marvel/DC comics are basically shit as poo, pish as piss its was rushed the art wrok was bad and so was the display of the characters, there are better crossovers. However it had its moments even though the battles were two pages.