All factions can also research a 30% increase to hull for all their ships.
Vasari and TEC can add 20% to shields, Advent can add 30% to shields.
Advent can add 4 extra armor, Vasari can add 5, TEC can add 6.
The Advent advantage in shields will probably narrow the gap substantially at level 10.
Take for example, the battleships at level 10, max research:
5460 hull, 3120 shield, 15.5 armor
Effective hull = 9692
Total effective HP: 12882
4030 hull, 4615 shield, 15.5 armor
Effective hull = 7153
Total effective HP: 11183
4940 hull, 3630 shield, 14 armor
Effective hull = 8398
Total effective HP: 12028
There are, however, more factors to consider such as shield mitigation, shield restoration rate, and supporting abilities (example, Kortul's Power Surge allows it to recharge its shields up to 225% faster).
Notable, of course, is the armor of the Kol and Radiance being equal at level 10. The Kol has 9.5 base armor, the additional 6 comes from research. The Radiance has 8.5 base armor, 4 comes from research, and the last 3 comes from Energy Absorptive Armor.