Who's the fatfag's choice of horse girls?

>>529211424
Are those worth more than 3* speeds? I have to admit I've basically just been focused purely on speed and nothing else.
What are the stat boosts for difference race tiers? particularly the A to S jump? and is there any horse we have at the moment who stands out at being someone who kinda just wants a bunch of race or strategy buffs to make something they're innately bad at higher?

What's a good stopping point for grinding speed? I feel like I ditch the rest to the point it causes problems and I have to take time to build up the rest of my non-speed friendships. I'm grinding Vodka and Urura at the moment but I'm scared to let either of them ease off speed training for anything