I have S7 titanium and the Ultra 2. The metal and black bezels feel bigger on the Ultra than the S7. The S10 has BIGGER black bezels and smaller metal than the S7. That is a step back in my opinion. My S7 has 100% battery and AC+ and is a good, slimmer, dressier companion to the Ultra 2.
If I were you, I would get the black Ultra 2 if you like that and keep your SS 7 for when you want a sleeker/smaller watch. The Ultra 2 will feel sooo different and the insane battery life, dual GPS, more nits, along with all and more that comes with the S10 makes it an easy decision. I would not get the S10 if I were you.