Everything is pretty much functional and therefore important. but id say if you had to order them shocks, springs, sway bars, bushings if your car is high mileage, then fine tuning things like camber kits, control arms, strut bars, end links and such, but you also have to take into consideration what suspension parts you already have, for example if your ride height has been lowered then camber kits are a good idea. end links can help get the most out of sway bars and strut bars can help if the sway bars aren't preventing as much body roll as you'd like
