I personally like jodhpur (short) boots with half chaps best for riding. You can get the right size for each part and I've always found them more comfortable. As each part wears you can replace it rather than replacing everything. And you can put the chaps over looser pants, like jeans or just pants, and still use them, but it's not as easy try to stuff them into tall boots. Also in the heat, after riding and at the stable removing the chaps makes a huge different in keeping cool
Tall boots have their place, but if you're serious about competing you'll probably have show boots anyway, as riding boots get scuffed up pretty quick.
I also like how I can just take off the chaps and then just have boots on I can do anything with. Whether it be walk a while, do barn work, climb a tree! I don't know, but I don't think I'd be as comfortable doing all that in tall boots.
It is really a personal choice though. Try on all your options and see what you like best.