I have 4 different shelters, one smaller hub, one bigger hub, one single flip-over, and an older Minuteman with a floor. I've used all of them this year depending on the conditions and if I'm going alone or taking the family.
If there's a foot of snow and you're walking a long way, you'll wish you had a hub. Dragging a flip-over a long way can tire you out before you even get to your spot. But if you want to move around, a flip-over is great to have. If I could only have one shelter, it would probably be the large hub, but I don't usually move a lot. There's just no easy answer for what's best. If you can't afford both right now, think about how you usually fish and under what conditions and decide what's best for you right now. No matter what you decide, there will be times when you wish you had the other one.