A little different perspective here, I have owned 3 Sprites, my brother has a TR3 he finished restoring over 20 years ago I have toured in it hundreds of miles and driven it quite a bit too. Others have described the cars differences well.
They are both great fun and very likeable cars probably two of the most charming cars in the popular brit sports car universe.
I am in the same boat as you, I have space and resources for one hobby car, or at least that is my quota if I want to continue to enjoy domestic bliss.
Life is short I loved my '67 Sprite, my '66 4A, my '54 AH 100 and my current car, the '68 TR250. I would not have owned the next one if I hadn't sold the one before. Some of those sales were hard decisions, but getting a "new" LBC is like falling in love like a teenager all over again.