Well, my thoughts on LA Ulm...
1) Rangers are very good. Everyone knows this. Moving on.
2) Your best bloodhunters (besides the Vampire Count) are B-enabled Fortune Tellers.
3) Your best Mage is, really, the Fortune Teller. You could even go with Misfortune scales to maximize the benefit of them.
4) The way to diversify LA Ulm's magic are Spectres. Vampire Counts have DD naturally, so can craft the Skull Staff, which gives them DDD to summon them. This is a very smart move. Unfortunately, I'm not sure what Dom3's Spectres have in the way of Magic picks. It seems that D is certainly fixed, but beyond that...
5) Having your Pretender able to summon in good mages (besides 4) above) while also working with your gem income would probably be the typical Lamia Queen. This generally means that you need NNNNDD on your Pretender, and you'll need BB as well for the Vampire Counts. It's generally rather funny how this directs your progress.
As far as Marignon goes:
The Goetic Master has one major weakness, and that's his old age. Unless you want to spend your blood slaves on keeping their age down, they will need to be seen as more or less expendable. As for myself, I generally do not like 'old' mages, which is a shame.
Otherwise, Marignon is fairly solid.
LA Abysia? I haven't played them enough to know, really.
If I think of any other LA Blood nations (Midgard is a very minor one, IIRC), I'll mention them later.