Not really, the +5 is slightly better mathematically, but only a tiny bit. It would prevent you from stacking Shield with things like Dodge, Silvery Barbs, or Blur. You would lose out on the reliability of the spell, since you couldn't wait to see if you get hit at all before using it (unless you reworded it's effect to force a reroll of the d20 that hit you, but even then, you could still be hit). These might be good things for your game, personally, I don't care if someone wants to use resources to avoid hit point damage; it's basically the same thing as using those same resources to heal hit point damage.
Really, my problem isn't with Shield, it's with the fact that at higher levels, you run out of good 1st-level spells to cast in combat. Right now, every Shield is one less Silvery Barbs or vice versa. My last character, a Wizard, did their level best to stay out of the firing line. I'd cast a Mage Armor as the start of day, and if something did target me, well, ok, I'd Shield it because there wasn't much else I had to work with at that level.
And on days when I didn't get targeted at all, I'd have open 1st level slots when everyone else is completely out of gas.*
*This depends on how your DM rules Magic Missile vs. Concentration- if it's three saves, there might be some niche use for the spell if you have to fight enemy casters.