Erm, here's an idea - we're both prone to textwalling (my fault really), and there's no real need. I realized that the whole "what's better" thing is the whole reason that I'm having problems with the wiki as it is. It's not that JJ Gnomes aren't the most strightforward, most well rounded and most easy to transition BM's - that's actually difficult to dispute.
The problem is that, and this is very clear on the issue of Bloodmage - is that Gnomes aren't nearly the only way to play them, and they kinda play them more like a gnome specific thing than a bloodmage specific thing. BM's get larger mana potions - but only the gnome and possibly the elf even care about that. For anyone else that just means you still get a fireball worth of mana (or thereabout) for a potion even with your lower mana pool. That can't be given top billing in "how to play a Bloodmage", even though not mentionig it is silly, because that's more like a "how to play a very cheezy gnome". The PQI will ask people to play all sorts of bloodmages - and the wiki would basically tell them to skip it as unfavourable if it wasn't Gnomes (especially before I changed it because Orcs weren't even listed).
Same thing with Orc crusaders, you can probably get your damage high as f**k with the Orc Crusader, but that's a VERY specific way to play a rather deep and open-ended class. Nobody would really play it like an Orc! So you can't have the wiki saying "Momentum is the most important ability" or only have Orcs listed as a good Crusader race - they're pretty much a complete anomaly.
The wiki as a whole is very misleading about most classes in this way and puts someone taking it seriously in the wrong frame of mind. That was what made me want to pull my hair out. I think it would be far more beneficial for the wiki to give tips on how to play various race-class combos (nice preps, favourable gods, stuff you like to find, etc.) for each race, rather than just list sinergistic ones - or make bold claims about them. I think I saw something like "The only race for Crusader is Orc" and that's complete BS - the only race which can attempt to cheeze momentum in a particular way is the Orc, but that's hardly the only way to play a Crusader and is VERY specific and narrow.
*And as for why gnome needs buildup, which is a silly debate - take this as a bit of a joke, even though it's partially true - the Orc BM asks 3 things 1) Do I have Pissorff, 2) Do I have B2P and 3) Where da bosses at? You can play him without being aware that you can boost sanguine, that you have a mana potion boost or any care about the size of your mana pool, really. Using a sigle neuron to consider anything else at all is more hassle than that in the literal sense.

(I'm obviously exaggerating, but unfortunately not by all that much). It's not that playing a JJ Gnome BM is particularly difficult or complicated or anything - it's that playing an Orc (or to a degree Halfling) is even simpler than that. I bet most of the time you don't even have to convert out of Binlor and just keep getting punished over and over and don't even bother with that. And that's the underlying power of any bloodmage - some preps or races can get more out of him, but you just don't need to, which makes those races a bad baseline or "default" BM. A Gnome BM is BM++ and, well, Gnome ++ when you get down to it. Interactions between mana potions and sanguine and stuff aren't universal at all, they're Gnome or possibly Elf shennanigans, but any Bloodmage at all can stick on a Health Pendant and/or the JJ health boost and go to town (Even Goblins, funnily enough). Orcs just kill 2 bosses at lvl 3 on average, while anyone else needs the whooping lvl 5.

* As a DD joke you can immagine a Gnome BM and an Elf BM talking about getting more about getting more out of your mana potions by boosting your mana pool, and the Halfling sitting at the table next to them spits his drink in shock and the Orc jumps up and yells "Wait, we have a mana pool now!?"