Your best option depends on what they are doing, and what they like to do to cover your options for getting up. I don't really have a super detailed guide for you here at the moment, but basically it comes down to who is playing the situation better. Rosalina is admittedly really dumb to deal with from the ledge, but you can get by her if you're careful.
Generally here are when your options are most useful.
Get up normally: When you see an attack coming that would hit you off the ledge and/or is laggy. You use your I-frames to ignore the attack and get up. If your timing is good and they are close enough, you can punish them for it as well. Best not to use this on attacks with low recovery or if they run offstage or something. It packs a lot of I frames, but you stand there for hours, it's too easy to time meaty hits when you aren't committed to something.
Get up attack: When for attacks near the ledge, you can try it on low recovery moves but it'll take good timing, the I frames on this option aren't great, you can even be hit before the attack comes out but they are enough to ignore an attack that isn't too active. Try this on players that like to time attacks to hit you just as your i frames wear off, or when they charge a smash right near the ledge, watch your spacing, and be careful on Yoshi's where your ledge attack has less horizontal reach. It takes forever for this animation to finish, on block or whiff it's a free smash attack from the entire cast; never use this unless you're sure it'll hit.
Get up roll: Good bit of I frames, but you can be hit mid-roll and it moves you further inside the stage. The cooldown isn't too bad but the roll itself takes a while and can be punished. This is best used when they are running offstage, or otherwise really close to the ledge. If you see them shield camping at the ledge or using an attack then this might work out for you.
Get up jump: Probably overall the fastest option and you can even airdodge to add some I frames or attack to add a hitbox, it's a fairly versatile option but it's also a huge commitment, you're in the air which exposes your blindspot and limits your options. You also have to land, meaning that you still haven't technically finished recovering yet. This is a good option if they aren't too close to the ledge or if they are but are busy waiting in shield for a ledge attack or something, you can be hit before you actually start the jump so don't use this if they are throwing out pokes at the ledge.
Ledge hopping: Faster than getting up but with no I-frames, not to be used if they are close enough to hit you out of your jump unless they already whiffed something big. You can land with auto-cancel Fair and Side-B from the ledge or you can try landing into shield or an evasive option, players love grabbing near the ledge landing into spot dodge isn't a bad idea if they look like they want to grab or dash attack. Adding the airdodge can make up for the lack of I frames but it's a massive commitment even with a cancel into a special. Though it can be useful for getting surprise damage or even a stock if you manage to land something like Bowser bomb or the klaw.
