2016 Tech champs: who to rank up?

Magrailothos

I've obtained a slightly stupid number of 2016 Tech 3-4 Rank-up gems clearing Variant content, and I'm wondering which of these old-but-now-buffed champs to use them on:

• Hulkbuster
  
• Ultron
  
• War Machine

I haven't used them all that much post-buff, and could do with a bit of guidance.

For reference, I'm TB who doesn't run suicides, currently clearing in 7.3. I'm looking for champions to help out in 7.3/7.4; and other late-game content.
And I've a crazy stockpile of Sig Stones, if anyone really needs a high Sig.


I've already have Vision Awakened at r5, and Star Lord and Kang at r4, so don't need to save the Gems for those options.

I have two rank-up gems left. My questions are:
1: what are your thoughts on the respective utility/damage/synergy value of these three recently-buffed champions?
2: Assuming that r4 is a stepping stone to r5, would you prioritise ranking up the Awakened 5* or the Unawakened 6*?

Main choices:
5* Ultron (Sig 40)
6* Ultron
5* War Machine (Sig 40)
6* War Machine
5* Hulkbuster (Sig 40)

Moosetiptronic

Did you have a 6* r3 hulkbuster? Ultron as a 6* is an immense choice. His sig is useful, but not essential and he's the best choice, currently, for 7.4 Kang, if you've not 100% 7.4.6 yet.

6* Ultron and if no 6* hulkbuster, then 5* HB for that 3-4 gem as his synergy with Ultron is part of what makes Ultron so nuts. High sig hulkbuster is no slouch either and it's very useful in Cav EQ.

Max sig Ultron as a 5* has some interesting utility, but if you've max sig guardian, bishop, torch, max sig Angela, kingpin, moleman, torch or shang, then you'd possibly use them instead for shock and incinerate challenges.

So 6* Ultron and 5* hulkbuster for synergy would be my move!