Blood Mage build diversity issue.

So there are these two nodes on Blood Mage ascendancy:
Vitality Siphon and Sunder The Flesh.
The former let you leech life to sustain yourself, the latter let you reliably crit for more effective leech and generate remnant to further heal. Both serve to equalize the downside that the mandatory ascendancy node Sanguimancy introduced.
The thing is for a caster class, there is no way to sustain without both of them active. And the ascendancy arrangement make it so such thing is only possible after the 4th ascend.
I tried to experiment with The Covenant chest piece after 3rd trial but 5% simply isn't enough, I get stuck at 1 HP for as long as I fight anything at the level of the 4th trial (80) thanks to their "leech resistance" being already at end game value. And sources of spell leech is practically nonexistence.

If you take at look at poe2.ninja/builds, there are 4 builds that take up 98%~ of Blood Mage total players: Lighting Spear, Rake, Arc and Spark.
For Lightning Spear and Rake, 97% are using Tangletongue.
For Arc and Spark, 96% allocate the four ascendancies: Sanguimancy, Vitality Siphon, Gore Spike and Sunder the Flesh.
When there are choices but statistic return such heavy bias, such choice are not meaningful because one is clearly better than other.

On the other note, Sanguimancy as it currently is does not feel good. This ascendancy point is a pure downside to the whole class, and builds have to find way to compromise for this massive downside to play. The node also mandate that every build of this ascendancy have to use Critical Hit mechanic for offense. Unlike Inquisitor from PoE1 who "reward" player to build crit, it is a requirement here, otherwise there would be no point to play this ascendancy at all. Hence why you see people stick to Tangletongue and Sunder the Flesh.

I won't provide any suggestion as this topic has been brought up many times and many ideas had been thrown out that I am sure some of them are better than what I can dream of coming up with on my own.
Just raise a flag and put it here as a notice, hopefully the ascendancy will become more fun next league.

Personal Tangent: